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Work, Energy and Simple Machines
Practice Test
I. Testing Concepts
Directions: Determine whether the italicized term makes each of the following statements true or false. If the
statement is true, write true in the blank. If the statement is false, write in the blank the term that makes the
statement true.
1. A device that does work with only one movement and changes the
size or direction of a force is a compound machine.
2. The greater mass a moving object has, the more kinetic energy it has.
3. A rock at the edge of a cliff has kinetic energy because of its position.
4. The output work of a machine compared to the input work is the
efficiency of the machine.
5. Energy that is stored is kinetic energy.
6. Mass is measured in joules.
7. The amount by which a machine multiplies an effort force is called
the work of the machine.
8. Chemical potential energy is energy stored in chemical bonds.
9. Thermal energy is energy stored by things that stretch or compress.
10. A slanted surface used to raise an object is called an inclined plane.
11. Two copies of the same book are in a book case. One book is twice as
high as the other. They have the same potential energy.
12. A toaster uses chemical energy to make toast.
13. The rate at which energy is converted is called power.
14. When a plant falls from a window its thermal energy is transformed
into kinetic energy.
15. The law of conservation of energy states that although energy can
change forms it can never be created or destroyed.
Directions: In the blank at left, write the letter of the term or phrase that correctly answers each question or
best completes each statement.
16. The unit of power is the
a. joule
b. MA
.
c. watt
d. second
17. Which of the following is not used to calculate potential energy?
a. mass
c. height
b. gravitational acceleration
d. speed
Work and Energy
37
18. Thermal energy is measured in
a. joules
b. N
.
c. ºC
d. j/kg
19. Three of these simple machines are similar to one another. Choose the one that
DOES NOT belong with this group.
a. pulley
c. lever
b. wheel and axle
d. wedge
20. The kinetic energy of an object increases as its
increases.
a. height above Earth
c. potential energy
b. speed
d. volume
21. Mechanical energy is the total kinetic and
a. thermal
b. chemical
energies in a system.
c. potential
d. electrical
22. Which of the following CANNOT be done by a simple machine?
a. increase the amount of work done
b. change the direction of a force
c. decrease the time it takes to do the work
d. transfer energy from one location to another
23. Green plants convert light energy from the sun into
.
a. gravitational potential energy
c. thermal energy
b. chemical potential energy
d. mechanical energy
24. The mechanical energy of a coconut falling from a tree
a. doesn’t exist
b. increases
c. decreases
.
d. remains constant
25. Which of the following groups of simple machines represent variations of an inclined
plane?
a. pulley, lever, and wedge
c. screw, wedge
b. pulley, wheel and axle
d. wheel and axle, screw
II. Understanding Concepts
Directions: Read the paragraph below. Use the information in the paragraph to answer questions 1 through 4.
A carpenter lifts a 10-kg piece of wood to his shoulder 1.5 m above the ground. He then sets the
wood on his truck at 1.0 m above the ground and makes his delivery going 10 m/s.
1. a. What is the wood’s potential energy on the carpenter’s shoulder?
b. On the truck?
2. What is the wood’s kinetic energy during the delivery?
3. If the wood drops from the carpenter’s shoulder, what would its maximum kinetic
energy be? (Hint: Use the law of conservation of energy.)
38 Work and Energy
Skill: Comparing and Contrasting
4. Why is the kinetic energy of the lumber higher on the truck during the delivery than when it
drops from the carpenter’s shoulder?
III. Applying Concepts
Writing Skills
Directions: Answer the following questions in complete sentences on the lines provided.
1. What is required for work to be done?
2. Explain the role friction plays in the conservation of energy.
3. Most Earth satellites follow an oval path rather than a circular path around Earth. The
potential energy of a satellite increases when the satellite moves farther from Earth. According
to the law of conservation of energy, does a satellite travel at it’s greatest speed when it is closest
to or farthest from Earth? Explain.
4. Why would adding oil to the moving parts of a machine increase its efficiency?
IV. Testing Concepts
Directions: In the blank, write the term that best completes each statement.
1.
energy is the energy an object has because of its motion.
2. Work is the transfer of
move.
3.
that occurs when a force makes an object
energy is stored energy due to position.
4. If work stays the same and distance is increased, then
needed.
force will be
5. Energy stored in chemical bonds is called
.
6. Anything that can fall has stored energy called
7.
8.
.
is the total amount of potential and kinetic energy in a system.
can be calculated by dividing the energy transferred by the time
needed for the transfer to occur.
9. Energy has different
, such as electrical, chemical, and thermal.
10. Kinetic energy depends on mass and
.
11. Machines can assist in doing work by increasing the force that can be applied to an object and
the distance over which the force can be applied.
12. GPE = mg
13. The instant an apple comes loose from an apple tree, it accelerates due to
.
14. As you ride on a swing set, your energy is constantly being converted from
to
and back again.
15. No matter how high you swing on a swing set, your
constant.
energy remains
16. Adding a lubricant can increase a machine's efficiency by reducing
17. The
get from various foods.
.
is a unit used by nutritionists to measure how much energy you
18. Friction converts
energy into
energy.
V. Understanding Concepts
Directions: List one form of energy into which electrical energy is converted by each of the following devices:
1. A radio
2. An electric fan
3. A space heater
VI. Applying Concepts
Writing Skills
Directions: Answer the following questions on the lines provided.
1. Analyze A friend rolls a bowling ball down a bowling alley. When the ball hits the pins, is the
bowler doing work on the ball? Why or why not?
2. Suppose you put your lunch up on a shelf. Name two kinds of energy it has, and explain why it
has them.
3. Analyze Two object are at two different heights above the ground.Which one has greater GPE?
Why?
4. Analyze Suppose you are opening a can of paint with a screwdriver. You push the tip of the
screwdriver between the can and its lid, then rock it up and down to pry the lid up a little,
then push it in more, and so on. Is the screwdriver being used as a simple or compound
machine? Why?
5. Explain Where does a car get the kinetic energy it has when it is moving forward?
6. Contrast the everyday definition of work with the scientific definition.
7. Explain If mass is converted into energy by the Sun, does that violate the law of conservation
of energy? Explain.
8. Analyze A person is standing still, waiting for a bus. Is that person using energy? Explain.