1
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
PRE-TEST
Directions: Answer the questions in the space provided.
1. Name the six simple machines.
2. Name the three parts of a lever.
3. What are the two kinds of pulleys?
4. How is a wheel and axle related to a lever?
5. What does it mean when a machine has a mechanical advantage?
6. How is the mechanical advantage of a movable pulley determined?
7. How is the mechanical advantage of a wheel and axle calculated?
8. What is a block and tackle?
9. How much effort is required to lift an object that weighs 100 pounds if you are using a
lever with an effort arm of five feet and a resistance arm of one foot?
10. What is energy?
“Work, Energy and the Simple Machines”
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
2
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
VIDEO QUIZ
At the end of the video presentation there will be a video quiz. You may use this worksheet to write your
responses to the questions from the video quiz.
1. The turning point of a lever is called the ___________.
a. resistance
b. effort
c. fulcrum
d. arm
2. The load or object being moved on a lever is called the ___________.
a. resistance
b. effort
c. fulcrum
d. arm
3. The mechanical advantage of a wheel and axle is determined by _________.
a. dividing the diameter of the wheel by the diameter of the axle
b. dividing the axle radius by the wheel radius
c. measuring the length of the effort arm
d. dividing the resistance arm by the effort arm
4. How do we calculate the mechanical advantage of a movable pulley?
a. Divide the length of the effort arm by the length of the resistance arm.
b. Divide the wheel radius by the axle radius.
c. Measure the length of the effort arm.
d. Count the number of supporting strands of rope.
5. How do we calculate the mechanical advantage of a lever?
a. Divide the length of the effort arm by the length of the resistance arm.
b. Divide the wheel radius by the axle radius.
c. Divide the length of the resistance arm by the length of the effort arm.
d. Divide the weight of the load by the effort arm.
6. What is energy? __________________________________________________________
7. How is a fixed pulley different from a movable pulley? ____________________________________
8. What is a block and tackle? ___________________________________________________
9. Name the six simple machines. _________________________________________________
10. There are three kinds of levers. What makes them different from each other?
“Work, Energy and the Simple Machines”
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
3
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
VOCABULARY
Directions: Match the definitions in column B with the words in column A. Write the
letter from column B next to the word in column A.
COLUMN A
COLUMN B
1. resistance _____
a. the ability to do work
2. effort _____
b. a pulley that makes work easier
3. fulcrum _____
c. the weight of the object being moved
4. energy _____
d. more than one pulley working together
5. fixed pulley _____
e. the force (push or pull) used to do
work
6. movable pulley _____
f. a pulley that changes direction of
effort but provides no mechanical
advantage
7. mechanical advantage _____
g. the turning point of a lever
8. block and tackle _____
h. when a machine multiplies the effort
being used
“Work, Energy and the Simple Machines
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
4
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
LEVERS
Levers were probably one of the very first machines.
There are three parts to every lever. One part is the object or weight being moved. It is called the “resistance.” A push or pull is needed to move the resistance. This push or pull is called the “force.” The third
part of the lever is called the “fulcrum.” It is the point on the lever where direction and movement
changes.
FORCE
RESISTANCE
FULCRUM
DIRECTIONS: Label the parts of each lever shown. Each lever will have a fulcrum, a resistance, and a
force.
Hammer
pulling nail
from a board
Pliers
Hammer
nailing
Broom
Moving a rock
with board and
log
Nutcracker
“Work, Energy and the Simple Machines”
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
5
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
LEVERS--THREE CLASSES
There are three classes or kinds of levers. They are called FIRST-CLASS, SECOND-CLASS, or THIRDCLASS LEVERS. What makes one class of lever different from another is where the force, resistance, and
fulcrum are located. Here are some examples:
First-class lever
In this case the fulcrum is located
between the force and resistance. A seesaw is a good example of a first-class
lever.
Second-class lever
A second-class lever is set-up so that the
resistance is between the force and fulcrum. A wheelbarrow is a second-class
lever.
Third-class lever
In the case of the third-class lever, the
force is between the resistance and the
fulcrum. A fishing pole is a good example.
DIRECTIONS: Identify the levers below as first-class, second-class, or third-class levers.
“Work, Energy and the Simple Machines”
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
6
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
TWO ARMS
All levers have two arms, called the effort arm and the resistance arm. The effort arm is the distance from
the fulcrum and the effort. The resistance arm is the distance from the fulcrum and the resistance.
Effort Arm
Resistance Arm
E
R
This equation can be used to find unknowns:
EFFORT FORCE X EFFORT ARM LENGTH = RESISTANCE FORCE X RESISTANCE ARM
LENGTH
Example: How much force is needed to move a rock that weighs 100 pounds using a lever with an effort
arm length of four feet and a resistance arm length of one foot?
4 ft
Solution:
100 lbs.
1 ft.
4 ft. x Fe = 100 lb. x 1 ft.
4ft. x Fe = 100 ft.-lbs.
Fe = 100 ft.-lbs. / 4 ft.
Fe = 25 lbs.
Directions: Solve the following problems.
1. The effort arm is eight meters long and the resistance arm is 1.5 meters long on a lever.
How much effort is needed to lift a 200 newton weight?
2.
Two boys want to balance a seesaw perfectly. One boy weighs 120 pounds and is sitting four
feet from the fulcrum. The other boy weighs 80 pounds. Where should the lighter boy sit to
balance the seesaw?
3.
A lever is being used to move a heavy stone from a garden. The stone weighs 250 newtons.
The board used as a lever is six meters long. If two of the board’s meters will be used as the
resistance arm how much force will be needed to move the rock?
“Work, Energy and the Simple Machines”
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
7
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
MECHANICAL ADVANTAGE OF A LEVER
The mechanical advantage (M.A.) of a lever is determined by dividing the length of the effort arm by the
length of the resistance arm.
Resistance
Arm
M.A. = Effort Arm/Resistance Arm
Effort Arm
M.A. = 6/1.5
M.A. = 4
1.5 m
6 meters
Example: What is the mechanical advantage for a lever with an effort arm of five meters and a resistance
arm of two meters?
Solution:
Effort arm = 5 m
Resistance arm = 2 m
M.A. = 5m/2m
M.A. = 2.5
This means the effort is multiplied by 2.5 when using this lever.
Directions: Try some mechanical advantage problems. Show work.
1. What is the M.A. of a lever with a resistance arm of 1.5 feet and an effort arm of three feet?
2. A lever has an effort arm of one meter. The resistance arm is .5 meters. What is the mechanical
advantage?
3. What is the mechanical advantage of a lever with a resistance arm of 1.2 meters and an effort arm of
three meters?
“Work, Energy and the Simple Machines”
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
8
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
MECHANICAL ADVANTAGE OF A WHEEL AND AXLE
The mechanical advantage (M.A.) for a wheel and axle is determined by dividing the diameter of the wheel
by the diameter of the axle.
Example: The diameter of a wheel is 25 cm and the diameter of the axle is 2 cm. What is the M.A. of the
wheel and axle?
Solution:
Diameter of wheel = 25 cm
Diameter of axle = 2 cm
M.A. = 25 cm/2 cm
M.A. = 12.5
Directions: Find the mechanical advantage of some wheel and axles from around your home. Here are
some suggestions. Make measurements carefully. Show work.
DOOR KNOB
BICYCLE (Pedals and Rear Sprocket)
PENCIL SHARPENER
“Work, Energy and the Simple Machines”
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
9
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
KINDS OF PULLEYS
DIRECTIONS: There are two kinds of pulleys. Do this experiment to find out about them. Answer the
questions in the Observation section.
Purpose:
To demonstrate the uses and advantages of fixed and movable pulleys.
Materials:
1.
2.
3.
4.
5.
6.
two single pulleys
twine
three heavy books
a spring scale
desk
ruler
Part A: FIXED PULLEY
Procedure: 1. Place the ruler over the edge of the desk and lay
two of the books on it so the ruler will stay in
place.
2. Take a pulley and attach it to the ruler with twine.
3. Tie twine around the other book and weigh the book
with the spring scale.
4. Feed twine through the pulley wheel. Tie one end of
the twine to the book. Tie the other end to the spring
scale.
5. Pull the spring scale to lift the book. Record reading
on scale.
Part B: MOVABLE PULLEY
Procedure: 1.
2.
3.
4.
Repeat step 1 under Part A.
Tie a long piece of twine to the end of the ruler.
Feed the twine through the pulley wheel.
Attach the book to the pulley and the spring
scale to the end of the twine.
5. Lift the book by pulling on the twine. Record
the spring scale reading.
Observations: Part A
1. What was the weight of the book? _________
2. What was the reading on the spring scale as
you lifted the book with the pulley? ________
Part B
1. What was the reading on the spring scale as
you lifted the book with this pulley? ________
“Work, Energy and the Simple Machines”
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
10
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
MECHANICAL ADVANTAGE OF PULLEYS
The mechanical advantage (M.A.) that we get from a pulley is based on the number of
supporting strands.
FIXED PULLEY
One supporting strand
M.A. = 1
Effort needed to lift 10 gram weight is 10 grams
MOVABLE PULLEY
Two supporting strands
M.A. = 2
Effort to lift 10 gram weight is 5 grams.
Directions: Identify the M.A. of these pulleys and calculate the amount of effort required to lift the
weight shown.
20 lb weight
“Work, Energy and the Simple Machines”
75 newtons
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.
11
Name ____________________
Work, Energy, and the Simple Machines: Lever, Wheel and Axle, Pulley
POST-TEST
DIRECTIONS: Answer these questions in the space provided.
1. Name the six simple machines.
2. Define these terms that are used in describing a lever:
a.fulcrum
__________________________________________________________
b.resistance __________________________________________________________
c. effort
__________________________________________________________
d.effort arm __________________________________________________________
e.resistance arm _______________________________________________________
3. There are three kinds or classes of levers. What makes one class of lever different from
another? ______________________________________________________________
4. Identify the resistance, effort, and fulcrum for these objects.
5. A 150 pound man is standing on a lever one foot from the fulcrum. How much effort must
be used to lift the man if the effort is applied six feet from the fulcrum?
6. How is the mechanical advantage of a wheel of axle calculated?
7. How is the mechanical advantage of a pulley determined?
8. What is a block and tackle?
9. How is a fixed pulley different from a movable pulley?
10. What is energy?
“Work, Energy and the Simple Machines”
©2001 Colgren Communications
All rights to print materials cleared for classroom duplication and distribution.