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Warm-Up:
Warm-Up:
1. Give an example of
something with speed.
2. Give an example of
something with velocity.
Warm-Up:
1. What would be the velocity
of a bird that flies 10 miles
South in 2 hours?
2. What is the acceleration of a
car that goes from a stop to
100km/h in 6 seconds?
Warm-Up:
1. What is the difference
between speed and velocity?
2. What is acceleration?
Speed is a rate
Speed =
distance
time
Average Speed =
total distance
total time
Velocity = speed in a particular
direction
Velocity changes if speed or direction
change
Acceleration: the rate at which
velocity changes
Acceleration=
final velocity – starting velocity
time it takes to change velocity
______ – distance over time
_______ – speed and direction
__________ – the rate at which velocity
changes
Calculate the total velocity for
each of the passengers.
0km/h west
5km/h east
4km/h west
Airplane: 800km/h west
QUICK REVIEW
What information must you know in order to
calculate speed?
What is the error in the following statement:
The velocity of the car is 55km/hr.
Cover the one you’re looking for.
D
S T
Application: Speed Calculations
1. A pitcher threw a baseball 150m in 2
seconds. How fast was the ball going?
2. A girl can run 50m/s. How long will it take
her to run 1000m?
3. You drove 80km/h for 3 hours. How far did
you go?
Application: Speed Calculations
1. A car drove 120 miles in 3 hours. How fast
was it going?
2. A sprinter can run 60 m/s. How long will it
take her to run 600m?
3. You drove 50 mi/h for 8 hours. How far did
you go?
Everybody Writes!
In your own words, describe the motion shown by each
graph. (Hint: Be sure to look at the labels on the x and y
axis.)
Graph 1
Everybody Writes!
In your own words, describe the motion shown by each
graph. (Hint: Be sure to look at the labels on the x and y
axis.)
Graph 2
Everybody Writes!
In your own words, describe the motion shown by each
graph. (Hint: Be sure to look at the labels on the x and y
axis.)
Graph 3
Everybody Writes!
In your own words, describe the motion shown by each
graph. (Hint: Be sure to look at the labels on the x and y
axis.)
Graph 4
Application: Speed Calculations
How fast would you have to drive to go from
Atlanta to New York (900 miles) in 10 hours?
A red car drove 150km at a speed of 50km/h. A
blue car drove 300km at a speed of 75km/h.
Which car reached its destination first?
Application: Speed Calculations
A plane flies 100 km east for 10 minutes, then
200 km for 10 minutes, and then 50 km for 5
minutes. What is the plane's average velocity?
Did the plane accelerate?
Application: Speed Calculations
You will drive to a town that is 100km away. Half
the trip you will be able to drive 100km/h (on the
highway) and half the trip you will drive 50km/h
(going through small towns). How long will it
take you to get there? Show your work!
1. Which car drove at a
constant speed?
2. Which car
accelerated?
3. Which car is faster?
How do you know?
4. Which car drove
farther after 1 hour?
After 6 hours?
---- Car 2
700
Distance (km)
Distance-Time
---- Car 1
Graph showing the
Graphs
speed of a car
600
500
400
300
200
100
0
1
2
3
4
Time (h)
5
6
7
Distance-Time Graphs
Calculate the average speed
at each point:
A._________
B._________
C._________
D._________
Did the car accelerate or stay
at a constant speed? How
do you know?
D
C
B
A
Distance-Time Graphs
The following graph shows the distance Kyle traveled on his bicycle trip
and the amount of time it took him to travel that distance.
1. During which 5-minute
interval did Kyle achieve
the greatest average
speed?
2. What may have
happened between t = 10
and t = 15 minutes?
1.
2.
3.
4.
5.
What two things must you know to calculate speed?
What is wrong with the following statement:
The velocity of a car is 100km/h
Turning left, slowing down, and speeding up are all examples of
__________.
How fast would you have to drive to go from Atlanta to New
York (900 miles) in 9 hours?
A red car drove 400km at a speed of 50km/h. A blue car drove
600km at a speed of 75km/h. Which car reached its destination
first? YOU MUST SHOW YOUR WORK FOR CREDIT!
8.
9.
10.
Which car drove the farthest after 1 hour?
How far did each car drive in 7 hours?
---- Blue
•
Red Car _____
Car
Graph showing the speed of cars
•
Blue Car: ____
---- Red
700
Which car
accelerated?
Which car stayed at
a constant speed?
What best explains
the motion of the red
car between t=1 and
t=4?
Distance (km)
6.
7.
Car
600
500
400
300
200
100
0
1
2
3
4
Time (h)
5
6
7
Practice:
A golf ball is hit north off a tee and 2
seconds later, it is traveling 300 m/s
Practice:
A car is traveling south at 20 mph and
after 10 seconds is traveling 60 mph
Target: (#21)
Read about the Great Pyramids on pg. 186.
1. What are the pyramids made from?
2. How did the Egyptians lift the blocks?
Warm-up:
What is work?
Notes: Work & Machines
Work occurs when a force causes an
object to move in the direction of the
force
Force & Motion must be in the same
direction for work to occur
Work = Force x Distance
Work is measured in joules (j)
Work = Force x Distance
1. How much work is done when you
apply a force of 10 N to lift a bag 1
meter?
2. How much work is done when a
force of 200 N is used to move a car 20
meters?
Power is the rate at which work is done
The unit for power is the watt.
Power =
Work
Time
Power =
Work
Time
3. If you do 60 J of work in 10 seconds,
what is your power?
Warm-Up:
1. How much work (in joules) does a
person do if they apply a 100N force a
distance of 10 meters?
2. How much power does a horse
generate if it does 600 joules of work in
60 seconds?
A machine is a device that makes work
easier by changing the size or direction of
the force
The work you do on a machine is called
the work input (input force).
The work done by the machine is called
work out put (output force).
Machines don’t reduce the work, they
change the size or direction of the
force
The force-distance trade-off: force or
distance can increase, but not together
Target
1. If you exert 10 N of force on an
object and the object does not move,
did you do any work?
2. What units are used for power?
Target (#24)
1. The work done on a machine is
called the __________ __________.
2. The work done by the machine is
called the ___________ _________.
The mechanical advantage tells you
how many times the machine
multiplies the force
MA =
Output Force
Input Force
Mechanical Efficiency compares work
output with work input.
ME =
Work Output X
Work Input
100
A lever is a bar that pivots around a
fixed point called a fulcrum
First class: fulcrum is between the
input force and the load
Second class: The load is between the
fulcrum and the input force
Third class: The input is between the
fulcrum and the load
Warm-Up:
1. If a car drives in a straight line and
its speed increases from 6m/s to 12m/s
in 3 seconds,
what is his acceleration?
2. If a ball rolls 10 meters in 2 seconds,
what is its velocity?
An inclined plane has a straight,
slanted surface
A wedge is a double inclined plane that
moves
A screw is an inclined plane wrapped in
a spiral
A wheel and axle consists of two
circular objects of different sizes
A pulley consists of a grooved wheel
that holds a rope or cable
A compound machine is made of two
or more simple machines
Target
1. What do machines do?
2. What is a compound machine?
Warm-Up
Warm Up
If it takes 100N to move a box,
how long will it take a 20W
motor to move the box 5m?
What is the efficiency of a block
and tackle if you pull 20m of
rope with a force of 600N to
raise a 200kg piano 5m?
Target (#26)
1. What is a simple machine that is flat
with a sloped surface?
2. Which simple machine uses a rope
and a grooved wheel?
Target (#28)
Tell which simple machine you would
use for each:
1. Hanging a flagpole
2. Loading a car onto a trailer
3. Drilling a hole in a board
4. Raising the sail of a boat
5. Moving a large rock
Warm-Up:
1. If you are riding a skateboard, are
you doing work? Explain.
2. If you ride a bicycle to school rather
than walk to school, are you doing less
work? Explain.
Copy these questions onto a separate
piece of paper:
1. What is a “Rube Goldberg
Machine”?
2. What chemical reaction did they
use?
3. List two simple machines in the
machine.
Target: (#33)
1. How much work is done if while
climbing the stairs you exert 500N of
force for a distance of 2M?
2. How much power do you generate if
it took you 10 seconds to do that?
Target:
1. If you did 1000 J of work on a box
using 500 N of force, what distance
would the box travel?
2. What is the power generated by 400
Joules of work for 40 seconds?
1. To determine the acceleration of an
object, you must calculate the change
in velocity during each unit of
___________.
2. What two things affect gravity?
3. Which kind of forces are exerted on
an object if there is a net force of zero
4.
Which two forces operate to keep a
moon in orbit around a planet?
A. inertia and gravity
B. inertia and friction
C. friction and gravity
D. distance and gravity
5. A complex machine is a system
made up of two or more simple
machines. Which of these machines
includes both a lever and a wedge?
A. wheelbarrow
B. scissors
C. doorknob
D. pencil sharpener
6. A wheel and axle is a simple machine made up of
two circular objects of different sizes. How does a
wheel and axle make work easier?
A. It changes the direction of the force
B. It multiplies the effort force.
C. It multiplies the distance over which the
force must be exerted.
D. It changes both the direction and the size of
the effort force.
1. A man applies a force of 500N to push a truck
100M down the street. How much work does
he do?
2. In which situation would you do more work:
-Lifting a 75N bowling ball 2M off the floor
-Lifting two 50N bowling balls 1M off the
floor
3. You push a 75N box 3M across the floor. How
much work have you done?
4. What is the power of a small motor that can
do 4500J of work in 25 seconds?
5. Work depends on _________and________.
6. Explain the difference between work & power.
7. You apply 200N to a machine, and the machine
applies 2000N to an object. What is its
mechanical advantage?
8. You apply 10 N to a machine, and the machine
applies 10N to another object. What is the
mechanical advantage? Can this machine be
useful? Why?
9. How does a machine make work easier?
10. List and gives of examples of the six simple
machines.
11. What is a compound machine?
Target: Copy these film questions:
1. What unit is used to measure the
diameter of an atom?
2. Where did the meter come from?
3. Why do we use the metric system?
4. What things do we measure the most?