Download Unit 7A packet—Motion

Unit 7A packet—Motion
Aristotle vs. Galileo Video- https://www.youtube.com/watch?v=2HR5UmG0q0s
1.
2.
3.
4.
5.
What did Aristotle say about falling objects?
What did Galileo believe?
How did he prove this?
What was his INDEPENDENT VARIABLE?
What did Galileo prove?
Apollo 15 proves Galileo (July 26, 1971, and ended on August 7)-- http://www.youtube.com/watch?v=03SPBXALJZI
BBC Video--Galileo
https://www.pinterest.com/pin/202662051958114939/
Choose a scientist to research and a creative project. Ideas for creative projects include: biography poster,
scrapbook, movie poster, children’s book, biography bag, paper doll set.
Check pinterest for ideas.
My scientist is: _______________________________
My project idea is: ___________________________
List the websites you get information from here:
Have you ever played baseball or picked up a book? Activities as simple as walking your dog involve forces. A force is
a push or a pull. A force may give an object energy or change its motion. Wind waves a flag on a flagpole. Engines run
our cars. Electromagnetic forces bond ions together to form compounds. Forces even slow you down. The force that
opposes the motion of an object is called friction. Friction is a force that brings an object to rest. When objects are in
constant contact with each other, friction acts into a direction opposite of the motion of the moving object, slowing the
object until it finally stops. There are 3 types of friction: Sliding friction, rolling friction, and fluid friction.
Sliding friction is when 2 solid surfaces slide past each other. When you move a chair across the floor, sliding friction
opposes your motion. The amount of sliding friction depends on the weight of the object that is moving and the type of
surface the object is sliding against. Rough surfaces apply more friction. A floor covered in carpet applies more friction
than a tile floor. Rolling friction is when an object rolls over a surface. Wheels are examples of rolling friction. Rolling
friction tends to oppose motion much less than sliding friction. This is why wheels are often used to move objects. Fluid
friction is when objects move thorough fluids such as liquids or gases. The fall of a feather is opposed by air resistance.
Fluid friction opposes motion even less than rolling friction. Lubricants can help reduce friction by changing sliding
friction to fluid friction. Oil, grease, and wax are examples of lubricants. Friction is not always bad. You want friction to
help your tires stop sliding on a wet road. Without friction, you could not walk. Think of how you easily you would be
able to walk on an ice skating rink.
Imagine a sunrise. What is moving? The sun or the Earth? You could look at it both ways! The object or point from
which movement is determined is called a frame of reference. The most common frame of reference is the earth itself.
Movement can only be measured with reference to something that is assumed to be fixed in place, this is called relative
motion. Examples:
 The earth is moving around the sun at a rate of about 18 miles per second and is spinning at about 1000 miles
per hour. Why don’t we feel like we are moving that fast?
 If you are driving down the highway with your family and your mom tells you to “sit still”, can you do it?
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
Draw an example of frame of reference.
Speed and Velocity
A runner gets from one place to another because they
moved or changed their position. Motion is a change in
position relative to a frame of reference. Motion is
measured by distance and time.
List 3 units to measure distance:
1.
2.
3.
List 3 units to measure time:
1.
2.
3.
Motion is a change in position relative to a frame of reference. Motion is
measured by distance and time. SPEED is the distance traveled by a moving
object per unit of time the object traveled.
𝑺𝒑𝒆𝒆𝒅 =
𝒅𝒊𝒔𝒕𝒂𝒏𝒄𝒆
𝒕𝒊𝒎𝒆
 Average speed is the total distance traveled divided by the total time
Example: If you traveled 100 miles in 2 hours, your average speed
would be 50 miles/hr.
 Constant speed is an unchanging speed. It is neither speeding up nor
slowing down. Slope can tell you about the speed of an object. The
steeper the slope, the greater the speed.
Example: If you have the “cruise” set in a car, then you are going a constant speed.
 Instantaneous speed is your speed at any given moment.
Example: If you are speeding up and your speedometer in the car says you are traveling 25 miles per hour, then
25 mi/hr is your instantaneous speed.
Domino Dash (COPY IN JOURNAL)
Problem: to demonstrate the relationship between speed, time and distance.
Background information: Average speed is the rate of motion calculated by dividing the distance traveled by the amount of time it
takes to travel that distance.
(𝑡𝑜𝑡𝑎𝑙 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑟𝑎𝑣𝑒𝑙𝑒𝑑)
𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑠𝑝𝑒𝑒𝑑 =
𝑡𝑟𝑎𝑣𝑒𝑙 𝑡𝑖𝑚𝑒
If you let S stand for the average speed, d stand for distance, and t Stand for time, you can write this equation as follows.
𝑆=
𝑑
𝑡
Because average speed is calculated by dividing distance by time, its unit always will be a distance will be a distance unit divided by a
time unit.
Materials:
1 box of dominoes
stopwatch
meter stick
calculator
2
Procedure:
1.
2.
3.
4.
5.
6.
Set up all 28 dominoes with equal spacing between them. Set the dominoes in a straight line to cause a chain
reaction when the first domino is pushed.
Measure the length of the domino row. Record this data in the table.
Use the stopwatch to measure the time it takes for the entire row of dominoes to fall after the first domino is pushed.
Record the data.
Calculate the speed at which the dominoes fell. Record.
Set up another row of a DIFFERENT length. Repeat steps 3-4.
Repeat for total of 5 different trials.
Length of domino row (cm)
Speed of Falling Dominoes
Time to fall (sec)
Average speed of falling dominoes (cm/sec)
Data Analysis:
Make a line graph to show the relationship between the length of the domino row and the time it takes to fall. Put the length of
the row on the X-axis and the time to fall on the Y-axis.
1. How did we decide what to put on each axis?
2. What relationship do we see between variables? How does the independent variable affect the dependent variable?
Conclusions:
What effect does distance have on the speed of a moving object?
What effect does time have on the speed of a moving object?
Use your notes to fill in the graphic organizer.
Average speed
Description
Constant speed
Instantaneous speed
When used
Which definition of speed (average, constant, or instantaneous speed) did we use in this investigation? Explain why.
What was the independent variable in this experiment? ________________________________
What was the dependent variable in this experiment? __________________________________
What are some controlled variables in this experiment? _____________________________________________________
Why did we use a line graph to explain the data?
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Visual Vocabulary-use the following words and definitions to guide your illustrations.
Motion
Distance
Displacement
What is Speed?
Is when an object changes its position relative to a reference point.
Is how far an object has moved.
Is the distance and direction from a starting point.
It is the distance an object travels per unit of time – 60 mph
Rate
Formula
Constant Speed
Average speed
Instantaneous speed
any change over time
Speed = distance / time
Speed that doesn’t change over time
total distance / total time = Avg. Spd = Δ d / Δ t
Speed at a given point in time.
Graphing Distance and Time
Distance/position – time graph displays the motion of an object over time.
Distance is the dependent variable & goes on the vertical axis.
Time is the independent variable so it is placed on the horizontal axis.
I
Based on the graph,
1. Between what times is there no motion?
2. What is the speed in part A?
3. Look at all the different slopes on the graph. What
does the slope tell you?
120
120
20
100
100
15
10
5
0
Distance (Miles)
25
Distance (Miles)
Distance (Miles)
4. Distance vs. Time Graphs to remember (special cases)
80
60
40
20
0
0
5
Tim e (hours)
No speed = stopped
10
80
60
40
20
0
0
5
10
Tim e (hours)
Constant speed away from
starting point
0
5
10
Tim e (hours)
Constant speed back toward
starting point
4
100
Distance (Miles)
Distance (Miles)
200
150
100
50
80
60
40
20
0
0
0
5
10
Tim e (hours)
Speeding up
0
5
10
Tim e (hours)
Slowing down
?
7. Study the following
distance/time graph of a car’s trip
A. What was the car doing between 1 and 1.5 hours?
B. What was the car’s speed between 0 and 1 hours?
C. What was the car’s speed between 1 and 1.5 hours?
D. What was the car’s speed between 1.5 and 2 hours?
E. How long (in hours) was the total trip?
F. How many miles did the car travel?
G. Draw a line on the graph to indicate the car’s average speed. Calculate the car’s average speed.
Velocity - Speed with Direction
You may hear a meteorologist on the news telling you that a storm is moving West at 5 kilometers per hour. Velocity is
speed in a given direction. The direction can be a compass direction or any other descriptive phrase, such as down,
toward the wall, etc. Velocity can be fast or slow just like speed only a direction is added. So what happens if the storm
changes direction and starts to move to the south? No, the direction has changed, therefore the velocity has changed. Ex.
We know the earth’s crust moves, it’s just so slow we don’t notice.
They Might be Giants-Speed and Velocity http://www.youtube.com/watch?v=DRb5PSxJerM
1. What is the difference between speed and velocity?
2. Give an example of speed.
3. Give an example of velocity.
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Velocity is called a vector. Vectors are measurements that include a magnitude (amount) and a direction. Vectors can
be added.
Example:


If I row a canoe at a speed of 2 mi/hr against a current that is going 1 mi/hr, then my velocity is 1 mi/hr upstream.
If I turn around and row the canoe with a speed of 2 mi/hr with the current that is going 1 mi/hr, then my velocity is 3
mi/hr downstream.
:
2 mi/hr
1 mi/hr
2 mi/hr
1 mi/hr
1. Johnny is standing up on the school bus tossing a ball up and down in front of him.
a. Ginny is sitting on the bus watching the ball. What does she see?
b. Sarah is standing on the side of the road watching the ball as the school bus drives by.
What does she see?
c. Ginny’s frame of reference is _____________________ Sarah’s frame of reference is ___________________.
2. Do the following describe speed or velocity?
a. A car traveling at 75 mi/hr
b. An object falling downward at 15 m/s
c. A bird flying at 5 m/s southwest
d. A worm crawling at 0.5 cm/s
3. Give an example of an object that is changing velocity, but not changing its speed.
4. Jane walks at a rate of 3 m/s. While at the airport, she gets onto a travelator (“moving sidewalk”) traveling 2 m/s.
a. If she stands still while on the travelator, what will her velocity be?
b. If she walks while on the travelator, what will her velocity be?
c. Jane realized that she forgot her ticket and turns around on the travelator and walks the opposite direction.
What is her velocity now?
Using the speed/velocity formula
Speed (Velocity) =
𝑫𝒊𝒔𝒕𝒂𝒏𝒄𝒆
𝒕𝒊𝒎𝒆
plus direction
Note: this is the formula for average speed or constant speed, not instantaneous speed.
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Rearranging the speed formula
1. Solve for distance:
2. Solve for time:
Steps to solve problems:
1. Circle what you are asked to find (you may need to “translate”)
 How far = distance
 How fast = speed
 How long = time
2. Underline given facts with numbers and units and write the symbol above it.
3. Check that your units “match”.
4. Write down your formula and rearrange for what you’re asked to find.
5. Put in numbers for symbols and solve.
6. Check that you answered the question asked and that you included units with your answer.
Example 1: A car traveling at a constant 300 m/hr travels for 2.7 hours. How far will the car travel during this time?
Example 2: Marcos, on the DHS track team, can run 440 m in 1 minute and 20 seconds. What is his speed in m/s?
Example 3: A car traveling a constant 50 km/hr travels a distance of 320 km. How long did it take for the car to make this
trip?
:
1. Luke is getting his pilot’s license. He flies from Houston to San Antonio, a distance of 185 miles. If he makes
the flight in 1.75 hours, what is his average speed for the trip?
2. Beatrice runs 3 miles (1 mile = 1600 meters) every morning before school to train for the upcoming track season.
If she can run 3 meters per second, how long does it take her to complete her morning workout (in seconds)?
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3. A school bus travels 15 kilometers in 0.75 hours. What is the speed of the school bus?
4. An object travels at a speed of 50 km/hr for 24 hours. What distance does it cover?
5. A cyclist travels 10,000 meters at a speed of 2.5 m/sec. How long will it take to complete the trip?
Acceleration
NFL: the Science of Acceleration- http://www.nbclearn.com/nfl/cuecard/50770
1. What is kinematics?
2. What is velocity?
3. How is speed measured in the NFL?
4. What does acceleration describe?
5. What is the difference between acceleration and velocity?
CSI: Bullets a Flyin’
There’s been an assassination at the new Glendale football stadium. Somebody in the rafters shot a player standing on the
sidelines. The suspect managed to escape from the stadium before authorities could grab her/him.
The crime lab has done the math and it turns out that in order for this shot to be pulled off from the rafters the bullet had
to have an average speed of at least 500 m/s in order for it to break through the player’s helmet. Also, in order for the
bullet to reach that speed in time, it had to have an average acceleration of at least 350 m/s2.
You rounded up 4 suspects: Manny, Moe, Jack, and Larry. Each suspect has a different type of rifle. You take each rifle to
the shooting range and use special cameras to measure the distance the bullet has travelled over time. These observations
are recorded below.
Distance Bullet Traveled (m)
Time (s)
Manny
Moe
Jack
Larry
0
0
0
0
0
1
500
100
200
500
2
1000
300
500
1100
3
1500
1000
1000
1800
4
2000
1400
1700
2500
5
2500
1500
2000
3500
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1) Use the observations in the table above to complete the distance vs. time graph set up for you below. The line
for Larry’s gun has already been completed. You must create the lines for Manny, Moe and Jack. Be sure to label
your axes (including units) and give the graph a title.
?
4000
3500
3000
?
2500
2000
Larry
1500
1000
500
0
0
1
2
3
4
5
?
2) Use the slopes of each graph to calculate the average speed for each gun. Remember: Average speed = total
distance/total time. Show your calculations below and INCLUDE UNITS!!:
Manny =
Moe =
Jack =
Larry =
3) From your results in #2, who are the possible gunmen? Explain why.
2500
Bullet Speed (m/s)
2000
1250 m/s
1500
Manny
1000
Larry
500
0
0
1
2
3
4
5
Tim e (s)
Above is a graph of bullet speeds vs. time for Manny and Larry’s guns. Use this graph to answer the following questions.
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4) For each gun, describe whether the bullets are speeding up, slowing down, or moving at a constant speed. Also
describe whether the rate of acceleration is increasing, decreasing, or staying constant.
Manny’s gun =
Larry’s gun =
5) Calculate the average acceleration of the bullets from each gun. Include units! Remember: Ave. acceleration =
(Final speed – Initial speed) / Time
Manny =
Larry =
6) From these calculations, who must be the murderer? Explain why.
What’s the best part about riding a rollercoaster? The feeling you get as you speed down that first big hill! You are pulled up the first
hill at a constant velocity and as you descend the other side your velocity rapidly increases. At the bottom, you may make a sharp left
turn. Then, your velocity decreases as you climb the second hill. All though
a roller-coaster ride, you experience rapid changes in velocity.
Acceleration is the rate of change in velocity
Acceleration =
𝑓𝑖𝑛𝑎𝑙 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦−𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦
𝑓𝑖𝑛𝑎𝑙 𝑡𝑖𝑚𝑒−𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 𝑡𝑖𝑚𝑒
or A
=
𝑉𝑓−𝑉𝑖
∆𝑇
Positive acceleration is when speed is increasing in the positive
direction. It is a positive number with a positive slope.
Negative acceleration is when speed is decreasing in the positive
direction. It is a negative number with a negative slope. This is also
called DECLERATION.
Acceleration is a vector, so it has a direction associated with it. The direction of the acceleration vector depends on
whether the object is speeding up or slowing down.
!When an object changes speed or direction, it is acceleration.
Why is going around a curve at the same speed acceleration?
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Calculating Acceleration
𝑉𝑓 − 𝑉 𝑖
𝐴= 𝑓
𝑡 − 𝑡𝑖
Acceleration = “change in velocity / time”
Change in velocity = “final velocity – initial velocity”
vf stands for final velocity
vi stands for intial velocity.
Units of acceleration are in meters per second, per second or meters per second squared –m/s2.
We usually use m/s2 as our units in this class.
Example: if a toy car speeds up by 2m/s every second, its
acceleration will be 2 m/s/s, which can also be written as 2 m/s2
Steps to solve problems:
1. Circle what you are asked to find.
2. Underline given facts with numbers and units and write the symbol above it.
3. Check that your units “match”. (For acceleration, velocity and time units will not always match)
4. Write down your formula and rearrange for what you’re asked to find.
5. Put in numbers for symbols and solve.
6. Check that you answered the question asked and that you included units with your answer
Eample 1 : An object that can go from stop to 50 m/s in 5 seconds would have an acceleration of?
1. A Porsche can go from rest to 60 mi/s in 5.2 seconds. What is its acceleration?
2. A car going 22.2 m/s slows down to 10 m/s in 3 seconds. What is its acceleration?
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3. A skater increases her velocity from 2.0 m/s to 10.0 m/s in 3.0 seconds. What is the skater’s acceleration?
4. A car accelerates at a rate of 3.0 m/s2. If its original speed is 8.0 m/s, how many seconds will it take the
car to reach a final speed of 25.0 m/s?
5. While traveling along a highway a driver slows from 24 m/s to 15 m/s in 12 seconds. What is the
automobile’s acceleration? (Remember that a negative value indicates a slowing down or deceleration.)
6. A parachute on a racing dragster opens and changes the speed of the car from 85 m/s to 45 m/s in a
period of 4.5 seconds. What is the acceleration of the dragster?
Bill Nye-Momentum https://www.youtube.com/watch?v=217dpIeuPVQ
Video #1- Bill Nye “Momentum” (about 23 minutes)
Answer the following questions during the Bill Nye video. Yes
1. The faster you go the more _________________ you have.
2. Whenever an object is _____________ it has momentum.
3. The faster something is traveling, the more it weighs, and the more mass it has, the ____________of its momentum will transfer.
4. Why does the quarter only move a little bit?
5. If you added up all the momentum of all the pieces of the ornament and all the marbles, they would equal the ___________ amount
of momentum as when the ornament just bounced off the truck.
6. If you are not moving, then you have ______ momentum.
7. In a rocket, the momentum of the hot fuel going one way _______________ the momentum of the rocket going the other.
8. a. He is bouncing two different balls. The momentum of the individual pieces is _________ to the momentum of the bouncing ball.
b. That’s what we call _____________________ of momentum.
9. What makes a soap box car move? _______________
10. How can rockets zoom through space where there is nothing to push against?
11. What happens when you drop a tennis ball while it’s on top of a falling basketball and why?
12. Momentum depends on how much things ______________ and how ___________they’re moving.
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13. How is momentum used on a billiards table?
14. While you are in a moving car, you and the car / only you have momentum. (Circle one.)
15. When the car stops, you will keep moving. Which one of Newton’s laws is this? ________
(They don’t say this in the video. Do you remember?)
16. In croquet, the momentum of the mallet gets _________________ to the ball.
17. The momentum of the air in the balloon going one way __________ the momentum of the tape/straw/balloon assembly going the
other way.
18. Fly vs. Windshield: Whose momentum wins? ______________
19. Explain how one of the scenes in the music video involves momentum.
20. a. At the end Bill says “Excuse me, I’ve got some __________ and __________ to multiply.”
b. What variable would that give him? __________
c. What unit would it be measured in? _________
Momentum
The 100 kg fullback runs up the middle of the football field. Suddenly he collides with a 75 kg defensive back tackling him. The
more massive fullback is thrown back 2 meters! How is this possible? The answer is MOMENTUM. All moving objects have
MOMENTUM. Momentum is equal to the mass of an object multiplied by its velocity.
Momentum=mass * velocity
or
p= mv
Although the defensive back has less mass, he has more momentum because he is moving faster than the fullback. His greater velocity
makes up for his lower mass. Who would have more momentum if both players were moving at the same velocity?
The Law of Conservation of Momentum states THE TOTAL MOMENTUM OF ANY GROUP OF OBJECTS REMAINS THE
SAME UNLESS OUTSIDE FORCES ACT ON THE OBJECTS.
Think of a baseball bat meeting a baseball. What does the batter need to do to make the ball go the farthest? Why?
How is momentum transferred?
The more mass an object has, the higher its momentum.
Example: a Ford Focus traveling 50 mi/hr vs. a truck traveling 50 mi/hr
The faster an object is moving, the higher its momentum.
Example: A car traveling 10 mi/hr vs. that same car traveling 75 mi/hr
If an object is not moving, its momentum is zero.
Momentum is a vector – it has a direction. An object’s momentum is in the same direction as its velocity.
The unit we use for momentum (p) is kg · m/s
Example: What is the momentum of a 25 kg object traveling north at 42 m/s?
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LAB: Momentum Bashing
Introduction:
To better understand what happens in a car crash, it helps to see how force, inertia, and velocity are related in a property
called momentum. The amount of momentum that object has depends on its mass and velocity. In this activity, you will
determine how increasing mass affects the bashing power of marbles.
To find out how much momentum an object has, use the formula:
p (momentum) = mass x velocity
Pre-lab Questions: Answer in complete sentences.
1. What determines if one car has more momentum than another in a two-car collision?
2. Does increasing an object’s mass increase its momentum?
Materials
o Ruler with center groove
o 4 marbles of the same size
o 5-oz plastic cup
o Stop watch
o 3 beam balance or electronic scale
o Meter sticks
o Books to support track
Procedure
1.
2.
3.
4.
5.
6.
7.
8.
9.
Cut a 3.0 cm square section from the top of the cup (as shown to the right).
Place a ruler with one end on a textbook (about 3.0 cm height) and the other end resting on the desk.
Place the 3.0cm opening of the cup on top of the ruler end that is on the desk.
Place a meter stick alongside the cup to measure the distance (in cm) the cup moves.
Position one marble in the groove at the maximum height of the ruler.
Release the marble and observe the cup.
Measure the distance the cup moved to the nearest 0.1 cm.
Perform three trials for 1, 2, and 3 marbles and average the results.
Record your data in the table provided.
Data Table 1: Glass Marble – Distances
Distance Cup Moves (cm)
# of Marbles
Mass of
Marbles
Trial 1
Trial 2
Average Distance Cup Moves (cm)
Trial 3
1
2
3
Analysis – Answer in complete sentences in your journal p. _______
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1. Compare your data for the glass marbles and different sized marbles. How are the results different? Explain your
answer using concepts of momentum and inertia.
2. Describe the general relationship between the number of marbles hitting the cup and the distance the cup moves.
3. What if the cup were made out of steel? How would your data be different for the trials with the glass marbles?
Explain your answer using concepts of momentum and inertia.
4. Explain why a 40,000 kg truck traveling at 2 miles per hour has the same momentum as a 2,000 kg SUV traveling
at 40 miles per hour.
5. What is the momentum of a marble that has a mass of 1.2 kg and a velocity of +8.5m/s? Calculate the impulse
needed to stop this marble.
Momentum Practice problems
1. Imagine two cars on the road. A car with a mass of 700kg is traveling at a velocity of 30 km/hour toward another
car with a mass of 500kg. The second car is traveling at a velocity of 40 km/hour. Using the formula for
momentum (p=mv) which car has more momentum? What will be the outcome of this collision?
2.
Using the momentum formula, determine the momentum of a...
a. 60-kg halfback moving eastward at 9 m/s.
b. 1000-kg car moving northward at 20 m/s.
c. 40-kg freshman moving southward at 2 m/s.
3. How much momentum does a 25 kg mass moving at 25 m/s have?
4. How much momentum does a stationary 5500 kg mass have?
5. What is the velocity of a 5.5 kg object that has a momentum of 550 kg·m/s?
6. Compare the momentums of a 50 kg dolphin swimming at 16.4 m/s and a 4100 kg elephant walking 0.20 m/s.
7. An object has a momentum of 55 kg·m/s and hits a stationary object making the second object starts to move. If
the first object ends with a momentum of 13 kg·m/s, what is the momentum of the second object?
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Motion Test Review
Momentum—Calculate the following. Show your work and use correct units.
a. A 5.0 kg baby on a train moving eastward at 72 m/s
b. A 48.5 kg passenger on a train stopped on the tracks
c. A 0.8 kg kitten running to the left at 6.5 m/s
Speed —Calculate the following. Show your work and use correct units.
a. If a car travels 400 m in 20 seconds, how fast is it going?
b. If you move 50 m in 10 se, what is your speed?
Time—Calculate the following. Show your work and use correct units
a. How much time will it take for a bug to travel 5 meters across the floor if it is traveling at 1 m/s?
b. You need to get to class, 200 meters way, and you can only walk in the hallways about 1.5 m/s. How much time
will it take to get to your class?
Distance—Calculate the following. Show your work and use correct units.
a. How far can you get away from your little brother with a squirt gun filled with paint if you can travel at 3 m/s and
you have 15 s before he sees you?
b. How far can your little brother get if he can travel at 2.5 m/s and in 5 seconds you will discover that his squirt gun
is out of water?
Average speed
You leave your house at 7:30 a.m. to go to school. You arrive at school at 7:50 a.m. the school is 3 miles from your
house.
a. What was your average speed in mph?
b. If the speed limit on the road was 40 mph, how long should it take you?
c. Explain why your calculated time does not match the actual time it took to get to school.
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Table 1-Fill in the table
Motion
Formula
Units
Momentum
Speed
Acceleration
Average Speed
Define:
Constant Speed
Positive acceleration
Negative acceleration
Velocity
Acceleration
Deceleration
Frame of reference
An athlete sprints 100 meters in 12 seconds. She stops and does 20 push-ups in 88 seconds. She then jogs 1000 meters in
300 seconds. She walks another 500 meters in 400 seconds. Make a distance time graph of her motion. What is her
average speed?
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Unit 7B- Forces
Bill Nye—Motion & Force https://www.youtube.com/watch?v=HXtNwLGxu78
1. Listen carefully to the opening song and fill in the blank:
Inertia is a property of _________________________
2. What force was holding the anvil up? ____________________________
3. What force is pulling the anvil down? ______________________________
4. When he flicked the card where did the coin go to? _____________________________________
5. Whether moving or sitting still everything has _______________________________
6. The men who were trying to move the boxes read that:
Nothing gets moved unless it is P_____________________ or P_______________________
Newton’s Three Laws of Motion: Bill goes through the three laws of motion. Fill in the blanks.
Newton’s 1st Law of Motion
7. Things at rest, stay at _______________________
8. Things in motion stay in ____________________ unless acted upon by an outside force.
Newton’s 2nd Law of Motion
9. Force = _____________________ times acceleration.
Newton’s 3rd Law of Motion
10. For every action there is an equal and opposite ______________________________
_______ 11. What happened to the apple’s weight as the plane dived toward the ground?
A) Got large or heavier
B) got less or weightless
_______ 12. What happened to the apple’s weight as the plane rose up towards the sky?
A) Got large or heavier
B) got less or weightless
_______ 13. What do we measure mass in?
A. meters
B. Liters
C. Grams
14. Listen to the song and fill in the blank: We are all ________________________________.
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Forces
Have you picked up a book or moved a desk? Have you ever dug in the sand or played baseball? In each of these activities, a force is
involved. A force is a push or a pull. Forces give energy to and object and cause it to move or change its motion. All forces have
magnitude and direction. Examples of forces include wind pushing on a flag on the flag pole or the moon pulling on the oceans to
cause the tides. This energy can cause an object to start moving, stop moving or change direction.
Friction
The Greek philosopher Aristotle thought that in order to set an object in motion and keep it moving at a constant speed, a constant
force has to be added. If the force were removed, the object would come to a stop. Based on your everyday experiences this seems to
be true. However, in the seventeenth century, Isaac Newton proposed a different explanation for motion. He said that an object in
motion should keep a constant velocity moving in a straight line. In other words, objects do not come to rest on their own. So what’s
the deal here?
Friction of course! Friction is the force that brings an object to rest. Air resistance acts on objects and slows them down
through friction.
Balanced and Unbalanced Forces
If you were arm wrestling a friend and each of you was
exerting maximum force, but neither of you were moving.
There is force being applies, but no motion is occurring.
What’s up with that?! Equal forces being applied in
opposite directions result in no change in motion are called
balanced forces. Combined forces that are balanced are
always equal to zero. Describe what a game of tug of war
would look like if the forces were balanced.

Forces that are not equal and opposite are called
UNBALANCED FORCES. In unbalanced forces, one
force is greater than the other. This causes a change in
motion. When 2 unbalanced forces are exerted in
opposite directions, the combined force is the difference
between the 2 forces. If 2 unbalanced forces are exerted
in the SAME direction, then the combined force is the sum of the 2 forces. A net force is defined as
the sum of all the forces acting on an object. Force is measured in Newtons (N), after the famous scientist Isaac Newton.
Newton’s First Law--The Law of INERTIA
“Every object continues in a state of rest, or in a state of motion in a straight line at a constant speed, unless it is forced to
change that state by forces acting upon it.”
https://www.youtube.com/watch?v=CQYELiTtUs8 (9:32) https://www.youtube.com/watch?v=lbHt5mg_33w (4:27)
1.
2.
3.
4.
Who really came up with the Law of Inertia?
How do objects move?
Why do things eventually stop?
Why can’t you tell you are moving in an airplane?
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Newton’s 2nd Law
https://www.youtube.com/watch?v=3FQ58lVtbCg (9:48)
1. What is the formula for force?
2. What are the units for force in the long
form?
3. What is the unit in short form?
https://www.youtube.com/watch?v=3FQ58lVtbCg
(3:07)
4. Which one do you think will go farther?
(stop the video and make a prediction)
5. Which one went faster and farther? Why?
The relationship between force, mass and acceleration is stated in Newton’s 2nd Law of Motion.
Force = mass * acceleration or F = ma
When mass is in kilograms and acceleration is in m/s/s, the unit is Kgm/s2. This unit is cumbersome in a problem. Fortunately, we have a
simpler unit that means the same thing Newton (N).
Newton’s second law explains why a smaller car gets better gas mileage
than a larger car. According to the 2nd law, the car with the least mass
will require less force to make it accelerate than the larger car.
Remember that acceleration is a change in speed or direction. If an
object is moving in a curved path, its direction is constantly changing. It
is constantly accelerating. This means that an unbalanced force must
always be present when there is a change in speed or DIRECTION. The
acceleration is always in the direction of the unbalanced force.
•
If you apply more force to an object, it accelerates at a higher rate.
Three forms of the second law:
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Gravity & Free Fall
As we have heard, in the late 1500’s Galileo dropped 2 cannonballs at the same time from the top of the Leaning Tower of Pisa in
Italy. Each cannonball had a different mass. Legend tells us that both cannonballs landed at the same time, helping Galileo form his
hypothesis about the motion of falling objects.
All objects accelerate at the same weight regardless of their mass. The acceleration of falling objects is due to the force of
gravity between the object and the earth. This is known as ACCELERATION DUE TO GRAVITY. Gravity is the attractive force
between all objects in the universe is called gravity. Near the surface of the earth the acceleration due to gravity is 9.8 meters per
second per second or 9.8 m/s2. But this doesn’t make sense! You have seen that objects fall at different rates with your own eyes!! A
rock and a leaf certainly don’t fall at the same rate. As a leaf falls air resistance keeps the leaf from falling as a result of friction. Air
resistance also opposes the downward motion of a rock, but the shape of the leaf causes greater air resistance. As the object
accelerates through a fall, gravity gradually opposes air resistance until gravity finally overcomes air resistance. Once an object
reaches this velocity there is no further acceleration, it has said to have reached terminal velocity.
Isaac Newton proved that the force pulling an apple to the ground was the same force pulling the moon to the earth. Newton’s Law of
Universal Gravitation says that all objects in the universe attract one another by the force of gravity. The size of the force depends
on 2 factors: the masses of the objects and the distance between them.
Practice with Newton’s 2nd Law
1. How much force is required to accelerate a 2 kg mass at 3 m/s2?
2. Given a force of 100 N and an acceleration of 10 m/s2, what is the mass?
3. What is the acceleration of a 10 kg mass pushed by a 5 N force?
4. Given a force of 88 N and an acceleration of 4 m/s2, what is the mass?
5. How much force is required to accelerate a 12 kg mass at 5 m/s2?
6. What is the acceleration of a 5 kg mass pushed by a 10 N force?
Mass and Weight
Weight is a measure of the force of gravity on an object. Since weight is a force, its unit is Newtons (N). If your weight is 500 N on
Earth, would it be the same on the moon? Explain:
Your weight can also change depending where you are on the Earth. The farther you move from the center, the more your weight
decreases. Your weight can changes based on how much gravity is able to pull on you. Is there less of you on the moon or on top of a
mountain when you weigh less? Explain.
Before Newton, weight and mass were thought to be the same. Even today, many people refer to weight, but mean mass. Weight is a
measure of the force of gravity and mass is the amount of matter. So when you say you want to lose weight, what you are really
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referring to is mass. Are Mass and Weight related? Yes! Newton’s 2 nd law can be restated in terms of weight (they are both
measured in Newtons.
Weight = mass * acceleration due to gravity
Remember: the units for weight are Newtons and the units for mass are
grams.
Word Bank: terminal velocity, weight, inertia,
force
1.
_________________ is a push or pull that give energy to an object
2.
_________________ is the property of matter that tends to resist any change in motion
3.
When a falling object no longer accelerates, it has reached its _______________________________
4.
_________________ is a measure of the force of gravity on an object.
Gravity and weightlessness
Our everyday lives involve such activities as sitting, walking, picking up things from the ground and lying in bed. None of these
activities are possible in orbit. Once a spacecraft reaches orbit, everything inside it appears to be weightless. Anything (or anyone)
that is not tied down will float.
Astronauts first feel the effect of weightlessness when the rocket engines are turned off. Straight away, they begin to float, held down
only by seatbelts. Weightlessness allows astronauts to appear super-strong. They can lift objects that would be far too heavy to move
on Earth. But there are some drawbacks.
Without the effect of gravity, blood and other body fluids begin to flow towards the head. This can cause a feeling of stuffiness and
headaches. With no gravity to push against, bones and muscles can become weak. To stay fit, they have to exercise several hours each
day. This allows them to recover more quickly when they return to Earth.
In a shuttle or space station, there is no up or down. There is no difference between a floor and a ceiling. This can make astronauts feel
sick until they get used to this strange arrangement.
So, why doesn’t the Space Station or satellites in orbit fall to the Earth, and why do the astronauts and objects inside the ISS or other
spacecraft appear to be floating? Because of speed!
The astronauts, the ISS itself and other objects in Earth orbit aren’t floating, they are actually falling. But they don’t fall to the Earth
because of their huge orbital velocity. Instead, they fall around Earth. Objects in Earth orbit have to travel at least 28,160 km/h
(17,500 mph). So, as they accelerate towards the Earth, the Earth curves away beneath them and they never get any closer. Since the
astronauts have the same acceleration as the space station, they feel weightless.
Newton’s Third Law: Action and Reaction
https://www.youtube.com/watch?v=NfuKfbpkIrQ
7. Give another example of Newton’s 3rd law.
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https://www.youtube.com/watch?v=cP0Bb3WXJ_k
“For every action there is an equal and opposite reaction.”
In the past space travel was considered impossible because space is a vacuum. If space is a vacuum,
what can a rocket push against? When a rocket’s engine is trying to make it move in space, hot gases
are released in a downward direction. This results in an equal sized upward force on the rocket that
pushes it ahead. Another way to state the 3rd law is to say that for every force there is an equal and
opposite force. This means forces
come in pairs! The two forces in a pair
are called action and reaction. Every
time you walk you push against the
ground with a force and the Earth
pushes back with an equal and opposite force. If you move
forward, the Earth moves in the opposite direction! Since
the mass of the Earth is so large compared to your mass, the
movement is unobservable. Action and reaction forces act on
different objects, not on the same object. Therefore, the
forces cannot cancel because they act on different objects.
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