MOVING AND LIFTING WITH
SIMPLE MACHINES
Illinois Physical Science Applications in Agriculture Lesson B5–1 • Page 1
Student Learning Objectives. Instruction in this lesson should result in
students achieving the following objectives:
1 Identify the types (classes) of levers.
2 Determine the effects of lever design on lifting power.
3 Explain the relationship between levers and wheels.
4 Test the effectiveness of various pulley designs.
5 Calculate the mechanical advantage of an inclined plane.
Anticipated Problem: What are the classes of levers?
I. A lever is a rigid bar that turns around a pivot point, called the fulcrum.
A. The force (effort) applied raises a weight or overcomes a resistance (load).
B. The types of levers are based on the location of fulcrum, effort, and load.
1. Class I lever
a. The fulcrum positioned between the load and the effort.
b. Lever increases the effort and reverses the direction of motion.
2. Class II lever
a. The fulcrum positioned at one end of the lever and the effort at the other end.
b. The load lies somewhere between the fulcrum and effort.
c. Effort is always further from the fulcrum than the load.
3. Class III lever
a. The fulcrum placed at one end of lever but load is furthest from fulcrum.
b. Effort is between the fulcrum and load.
Anticipated Problem: What determines the effects of lever design on lifting power?
II. If a pushing or pulling force is applied at one end of a lever, an action is produced at
another point along the lever.
A. The point along the lever at which the effort is applied is just as important as the effort
applied.
1. When effort is applied further from the fulcrum than the position of the load, less
effort is required to raise the load.
2. The effort must move a greater distance to raise the load.
3. Effort distance and load distance depend upon the position of the fulcrum.
B. The principle of lever states that the effort multiplied by its distance from the fulcrum
is equal to the load multiplied by its distance from the fulcrum.
1. Resistance force (resistance distance) = effort force (effort distance)
2. Work=force (distance). The work done at one end of lever equals work done at the
other end of the lever.
3. A 100-pound block positioned 2 ft. From fulcrum of a 10-foot lever would require
only 25 pounds of effort force. (100(2) = 25(8))
Anticipated Problem: What is the relationship between levers and wheels?
III. Wheels are actually rotating levers.
A. The center of the wheel is the fulcrum.
B. The radius of the wheel is the bar of the lever.
C. The axle rotates a shorter distance than the wheel but has greater force.
D. Turning the wheel causes the wheel to move a greater distance but less force.
Anticipated Problem: How effective are various pulley designs?
IV. A pulley is a class I lever.
A. Pulley—A small wheel used to change direction or increase an applied force.
1. A stationary pulley does not offer a mechanical advantage of force. They simply
change the direction.
a. How the machines multiply the force that they receive.
2. Moveable pulleys multiply effort force.
a. The effort distance is greater and the resistance distance is less.
b. On a single moveable pulley the effort force will be half the load and the effort
distance will be twice the load distance.
3. Multiple pulleys can reduce the effort force required to lift.
a. Multiplication of force is equal to the number of sections of rope that raise the
lower set of pulleys attached to a load.
Anticipated Problem: What is the mechanical advantage of an inclined plane?
V. Inclined planes make it possible to move a load with less effort than lifting the load
vertically.
A. Inclined plane—Formed by placing a flat surface at an angle to another surface.
B. The smaller the slope of the inclined plane, the less effort required to move the load.
C. To calculate effort forces to move the load remember this formula.
1. Effort force × effort distance = load force × load distance
MOVING AND LIFTING WITH
SIMPLE MACHINES
Part One: Matching
Instructions: Match the word with the correct definition.
a. Effort
d. Lever
g. Pulley
b. Fulcrum
e. Load
h. Wheel
c. Inclined plane f. Mechanical advantage
_______1. Formed by placing a flat surface at an angle to another surface.
_______2. How machines multiply the force that they receive.
_______3. A small wheel used to change direction or increase an applied force.
_______4. Rotating levers.
_______5. Resistance part of a lever system.
_______6. The force that is applied to raise or move a load.
_______7. A rigid bar that turns around a pivot point.
_______8. The pivot point of a lever system.
Part Two: Fill-in-the-Blank
Instructions: Complete the following statements.
1. The type of lever is based on the location of the _____________, _____________, and the
______________.
2. The principle of a lever is the sum of effort distance times effort force is equal to
_____________________________ distances times _____________ force.
3. The center of a wheel is the ______________.
4. A ______________ pulley does not offer any mechanical advantage.
Illinois Physical Science Applications in Agriculture Lesson B5–1 • Page 8
5. ______________ pulleys can reduce the effort force required to lift the load.
6. ______________ _______________ make is possible to lift a load with less effort force.
Part Three: Multiple Choice
Instructions: Write the letter of the correct answer.
_______1. The class I lever has the ______________ in the middle of the lever.
a. load
b. fulcrum
c. effort
_______2. The class II lever has the _____________ in the middle of the lever.
a. load
b. fulcrum
c. effort
_______3. The class III lever has the ______________ in the middle of the lever.
a. load
b. fulcrum
c. effort
_______4. A pulley is a class __________ lever.
a. I
b. II
c. III
_______5. The less slope of an inclined plane will require ______________ effort to lift the load.
a. more
b. equal
c. less
d. varies
_______6. What is the force with which gravity pulls on an object called?
a. pulley
b. kinetic energy
c. weight
d. lever
_______7. What is the push or pull that makes an object move, slow down or stop called?
a. pulley
b. kinetic energy
c. force
d. weight
_______8. Which of the following statements is false?
a. Mechanical machines can convert movement from one direction to another.
b. Applying force to a machine gives it energy.
c. The total energy in the machine system varies as the machine does work.
d. Effort is the force that is applied to a machine to produce an action.
Illinois Physical Science Applications in Agriculture Lesson B5–1 • Page 9
_______9. A lever that has the fulcrum at one end of the lever and the effort at the other is what
class of a lever?
a. First class lever
b. Second class lever
c. Third class lever
d. Fourth class lever
______10. Which of the following statements is false?
a. Single pulleys create a change in the direction of a force.
b. Friction reduces efficiency in all machines.
c. A single pulley consists of a wheel and a rope or similar material.
d. Single pulleys can alter the magnitude of the force.
______11. Which of the following is not an example of a simple machine?
a. lever
b. car
c. wheel
d. pulley
______12. A log splitter would be classified as which of the following simple machines?
a. wedge
b. screw
c. inclined plane
d. lever
______13. The formula for work is:
a. distance divided by time
b. distance minus force
c. distance times force
d. distance divided by force
______14. A flat surface that is positioned at any angle other than a right angle to a horizontal
surface is called a:
a. friction
b. inclined plan
c. mechanical advantage
d. slope
______15. Which of the following terms describes the resistive forces opposing the motion of two
bodies in contact with each other?
a. friction
b. inclined plane
c. mechanical advantage
d. slope
______16. Which of the following statements is NOT true?
a. Ramps reduce the amount of overall work that is required to move an object.
b. A ramp is an example of a stationary inclined plane.
c. An inclined plane makes it possible to raise a large force with a smaller force.
d. Ramps change the way work is done.
Illinois Physical Science Applications in Agriculture Lesson B5–1 • Page 10
______17. The friction associated with a circular body rolling over another surface is called:
a. static friction
b. sliding friction
c. rolling friction
d. pulling friction
______18. The number of times the resistance force is greater than the effort force, this is known
as:
a. friction
b. mechanical advantage
c. slope
d. pulley force
______19. A plow is an example of which of the following simple machines?
a. pulley
b. wedge
c. inclined plane
d. wheel and axle
Part Four: Short Answer
Instructions: Answer the following questions.
1. Describe a class I lever.
2. What effect does the effort distance have on the effort required to raise the load?
3. Why does a moveable pulley reduce the effort force?
4. What is the formula to calculate mechanical advantage of an inclined plane?
Illinois Physical Science Applications in Agriculture Lesson B5–1 • Page 11
Assessment
Illinois Physical Science Applications in Agriculture Lesson B5–1 • Page 28
TS–A
Technical Supplement
MOVING AND LIFTING WITH
SIMPLE MACHINES
1. What is a lever?
A lever is a mechanical device consisting of a bar turning around a fixed point (fulcrum)
using a force applied at a second point to lift an object at a third point. Levers are the
simplest machines, usually composed of a bar or rod that tilts on a pivot. The force
applied to the lever is called the effort. The object being moved and the resistance to
movement are called the load.
2. There are three types of levers:
First class lever: the fulcrum is placed between the effort and load. These levers
are used to gain speed, to gain force, or to change direction.
Second class lever; the fulcrum is at one end of the bar, the effort is applied at the
other end with the load in between. A second class lever has a mechanical advantage
greater than one, but cannot be used to gain speed or change direction.
Third class lever: the fulcrum is at one end of the bar; the load is at the other with
effort in between. Third class levers are only used to gain speed.
Illinois Physical Science Applications in Agriculture Lesson B5–1 • Page 29
3. How does the size and design of a lever affect its lifting power?
Lever power can be described in the following equation:
Fe × De = Fl × Dl
F = force
D = distance
e = effort
l = load
First Class Levers:
If the fulcrum is centered between the effort and load, the effort required to
raise the load is equal to the weight of the load.
The effort is twice as far from the fulcrum as the load, the effort is half the
amount of the load.
The effort is twice as close to the fulcrum as the load, the effort is twice the
amount of the load.
Second Class Levers:
If the effort is three times as far from the fulcrum as the load, the force needed
to raise the load is one-third of the load.
Third Class Levers:
If the effort is one-third as far from the fulcrum as the load, the force needed to
raise the load is one-third of the load.
4. Why does a pulley decrease the effort required to lift an object?
(applied force) × (applied distance) = (output force) × (output distance) A pulley
multiplies force at the expense of distance. The applied distance is increased, so the
applied force is decreased while the work output remains the same. For example, if a
person pulls ten meters of rope with a force of fifty pounds, the person will lift a five
hundred pound object one meter. 10M×50 lbs = 1 M × 500 lbs
Illinois Physical Science Applications in Agriculture Lesson B5–1 • Page 30
5. Why do wheels make moving objects easier?
Wheels are actually rotating levers. The center of the wheel is the fulcrum. The axle
is the effort and the outer part of the wheel is the load. The movement of the wheel is
turned into a shorter but more powerful movement at the axle.
6. Where are levers, pulleys and wheels used in agriculture?
Levers: balance, pliers, wheel barrow, hammer. front end loader, wrecking bar
Pulleys: block and tackle, mower deck, chain hoists, elevators
Wheels: screwdriver, steering wheel, faucet, vehicle wheels
Illinois Physical Science Applications in Agriculture Lesson B5–1 • Page 31