Download Forces and Motion-part 1 2015

Science 10/7/15 Force and Motion
Day #1
• >Pick up the “Force and Motion” Concept
Review from the cart and write your name on
it!
• >Clear your desk and get ready to learn some
new concepts!
• The learning objective for today is to learn the
vocabulary necessary for tomorrow’s outside
activity.
Forces and Motion Terms and
vocabulary
Review Concepts
What is motion?
• Motion is a change in position.
• An object changes position if it moves relative
to a reference point.
Reference Point
Distance
• Distance is the length of the route you travel.
Starting Point
To find the distance I’ve traveled, I measure
my path from my starting point to my ending
point.
Ending Point
Distance
• Distance is the length of the route you travel.
Starting Point
150 meters
To find the distance I’ve traveled, I measure
my path from my starting point to my ending
point.
50 meters
Ending Point
Distance
• Distance is the length of the route you travel.
Starting Point
150 meters
Displacement 10 cm SE
To find the distance I’ve traveled, I measure
my path from my starting point to my ending
point.
50 meters
Total Distance=200 meters
Ending Point
Displacement
• Displacement is the difference in position between
your starting point and your ending point. It has a
direction.
• What is the displacement here?
Displacement
• Displacement is the difference in position between
your starting point and your ending point. It has a
direction.
• What is the displacement here?
200 m
75 m
75 m
200 m
• My displacement would be 0 m because I
started and ended at the same spot.
• My distance would be the length of the path
that I traveled. The distance is 550 m.
• You are a truck driver. If you were getting paid
by the mile for your travel, would you rather
have your distance or your displacement
measured for round trips? Explain…..
• My displacement would be 0 m because I
started and ended at the same spot.
• My distance would be the length of the path
that I traveled. The distance is 550 m.
• You are a truck driver. If you were getting paid
by the mile for your travel, would you rather
have your distance or your displacement
measured for round trips? Explain…..
You would rather be paid by your distance travelled, it is
always at least as far as the displacement.
How would you measure displacement
here? How would you measure
distance?
Distance=total length travelled
Displacement=distance from the beginning point to the
end point.
Use your ruler to measure on your paper now.
How would you measure displacement
here? How would you measure
distance?
Distance=total length travelled = 13.5 cm
Displacement=distance from the beginning point to the
end point. 10 cm
8.5 cm
8.5 cm + 5 cm = 13.5 cm
How would you measure displacement
here? How would you measure
distance?
5 cm
Measure the distance and displacement for this example in centimeters. One
centimeter = 1 mile
Measure the distance and displacement for this example in centimeters. One
centimeter = 1 mile
10 cm
11 cm
10 cm
10 cm + 11 cm + 10 cm= 31 cm or 31 miles
Speed
• Speed is how fast something is moving.
• Speed = Distance divided by Time
• Try these:
1. What is the speed of a car that has traveled
300 miles between the hours of 5:00 P.M. and
9:00 P.M.?
2. Drew drove from Wauconda to Crystal Lake in
25 minutes. He traveled a total of 10 miles to his
destination. What was his average speed?
Speed
• Speed is how fast something is moving.
• Speed = Distance divided by Time
• Try these:
1. What is the speed of a car that has traveled 300
miles between the hours of 5:00 P.M. and 9:00
P.M.? 300 miles / 4 hours= 75mph
2. Drew drove from Wauconda to Crystal Lake in 25
minutes. He traveled a total of 10 miles to his
destination. What was his average speed?
10 miles / 25 minutes= .4 miles/min.
Average Speed Vs.
Instantaneous Speed
• What is the difference between these two
types of speed? Give an example….
Average Speed Vs.
Instantaneous Speed
• What is the difference between these two
types of speed? Give an example….
Average speed =the runners ran 100 meters in 10 seconds or 10 m/s average
Instantaneous Speed= The bullet cut through the apples at a speed of 5,000 m/s
Constant Speed
•?
Constant Speed
• Your cruise control on your car allows you to
drive at a constant speed. It stays the same
over time.
Were you right?
• Instantaneous speed is your speed at any
given moment in time.
• Average speed is the average of your speed
over a certain distance.
1. When a police officer pulls your dad or
mom over for speeding, is he measuring
instantaneous speed or average speed?
Were you right?
• Instantaneous speed is your speed at any given moment in
time.
• Average speed is the average of your speed over a certain
distance.
1. When a police officer pulls your dad or mom over for
speeding, is he measuring instantaneous speed or average
speed?
>Instantaneous Speed: It is how fast your dad was going the
instant that he clocked him with
the “radar gun”.
Graphing
• If you are given the
following information, could
you graph it? Let’s try…..
• You need:
–
–
–
–
–
Title
Time(horizontal axis)
Distance(vertical axis)
Units
Spread out your numbers
Distance
(M)
Time
(Sec)
0M
0 Sec
30 M
1 Sec
60 M
2 Sec
100 M
5 Sec
Average Speed (Distance vs Time)
Velocity Vs. Speed
• What is the difference between velocity and
speed?
• What do they have in common?
Velocity Vs. Speed
• What is the difference between velocity and
speed? One has direction (velocity)
• What do they have in common? speed
• Both velocity and speed are how fast an
object is moving.
• The difference is that velocity also has a
direction.
• For example, my speed is 50 m/s.
• My velocity is 50 m/s north.
Acceleration
• Acceleration is your change in velocity divided by the time it
takes for the change to occur.
•
(final speed – initial speed)
•
time
• What would be my car’s acceleration if its final speed was 50
MPH and its initial speed was 2 MPH over 6 seconds?
Acceleration
• Acceleration is your change in velocity divided by the time it
takes for the change to occur.
•
(final speed – initial speed)
•
time
• What would be my car’s acceleration if its final speed was 50
MPH and its initial speed was 2 MPH over 6 seconds?
Acceleration
• Acceleration is your change in velocity divided by the time it
takes for the change to occur.
•
(final speed – initial speed)
•
time
• What would be my car’s acceleration if its final speed was 50
MPH and its initial speed was 2 MPH over 6 seconds?
50 MPH - 2 MPH / 6 seconds= 8 MPH / sec /sec
Types of Acceleration
• There are three types of acceleration:
– Speeding up
– Slowing down
– Changing Direction
Positive and Negative Acceleration
• Positive acceleration occurs when you are
speeding up.
• Negative acceleration occurs when you are
slowing down.
Mass, Momentum, and Inertia
What are they?
• Mass is the amount of matter in an object.
Which would have more mass, a cotton ball or
a lead ball the same size? The lead ball
• An object that is small may have more mass
than an object that is bigger. It just depends
on what it is made of.
• Inertia is the tendency of an object to resist a
change in its motion.
• The more mass an object has, the harder to
speed it up, slow it down, or turn it. It has
more inertia.
Momentum
• Momentum is a measure of how hard it is to
stop an object.
• Momentum is calculated: Mass X Velocity
What is the momentum of a car with a mass
of 30,000 KG and a velocity of 10 kilometers
per hour? What are the units?
Conservation of Momentum
• The total momentum of objects that collide
with each other is the same before and after
the collision.
• What lab did we do showed this?
• What happened?
• How is this principle applied to bowling,
billiards, etc.?
Newton’s First Law
• What is Newton’s First Law?
If there is no net force acting on an object, the
object remains at rest. If the object is moving,
it continues to move in a straight line with
constant speed unless acted upon by a force.
What are some examples that show this?
Newton’s Second Law
• What is Newton’s Second Law?
Acceleration of an object depends on the
force that is applied to an object
How does this law relate to sports you know?
Newton’s Third Law
• What is Newton’s Third Law?
For every action, there is an opposite and
equal reaction
What are some examples of this?
Friction
What are the three types of
friction?
• Static friction: the type of friction that prevents
an object from moving when a force is applied
• Rolling friction: the type of friction that helps a
wheel turn and keeps the tire from slipping on
the ground
• Sliding friction: the type of friction that slows
down an object that slides
What are some examples of each in sports?
Forces That Act on Objects
• Gravity: the force that acts between any two
objects that have mass
• Friction: ???
• Air Resistance: a form of friction that acts to
slow down any object moving in the air
Force
• Force is measured in newtons (N).
• We use a spring scale to measure newtons.
When did we do that?
Catapults/Trebuchets
• You need to be able to identify the following
parts:
throwing arm frame
base
projectile
counterweight axle arm
rubber band projectile cup release angle
Counterweight arm sling
Let’s see what you can do……
Catapults and Trebuchets