Name
Period
Date
Energy Worksheet 4 Energy Storage Mechanisms and
Total Mechanical Energy
1. Read each of the following statements and identify them as having to do with kinetic
energy E k  , gravitational potential energy E g  , elastic potential energy Ee  ,
dissipated energy E diss  , or some combination.
E k , E g , E diss
or Ee ?
Statement:
a. If an object is at rest, it certainly does NOT store any of this
energy.
b. Depends upon object mass and object height.
c.
The energy an object possesses due to its motion.
d. The amount is expressed using the unit Joule (abbreviated J).
e. The energy stored in an object due to its height.
f.
The amount depends upon the arbitrarily assigned zero level.
g. Depends upon object mass and object speed.
h. If an object is at rest on the ground (zero height), it certainly
does NOT store any of this energy.
i. Depends on how much an attached spring is stretched or
compressed and the strength of the spring.
j. Depends on how much friction exists and the distance over
which that friction acts.
k. An object slides down a rough incline.
2. A toy car is moving along with 0.40 Joules of kinetic energy. If its speed is doubled,
then its new kinetic energy will be _______. Explain your answer.
3. A young boy's glider is soaring through the air, possessing 0.80 Joules of gravitational
potential energy. If its speed is doubled and its height is doubled, then the new
gravitational potential energy will be _______. Explain your answer.
4. Which would ALWAYS be true of an object possessing a kinetic energy of 0 Joules?
a. It is on the ground.
b. It is at rest.
c. It is moving on the ground.
d. It is moving.
e. It is accelerating. f. It is at rest above ground level.
g. It is above the ground. h. It is moving above ground level.
© The Physics Classroom, 2009
Energy WS 4
page 2
5. Which would ALWAYS be true of an object possessing a gravitational potential
energy of 0 Joules?
a. It is on the ground.
b. It is at rest.
c. It is moving on the ground
d. It is moving.
e. It is accelerating. f. It is at rest above ground level
g. It is above the ground. h. It is moving above ground level.
6. A mass is attached to a spring of spring constant k, resulting in 0.50 J of elastic
potential energy. If the spring is stretched twice as far, the new elastic potential
energy will be _______. Explain your answer
7. Calculate the kinetic energy of a 5.2 kg object moving at 2.4 m .
s
8. Calculate the gravitational potential energy of a 5.2 kg object positioned 5.8 m above
the ground.
9. Calculate the speed of a 5.2 kg object that possesses 26.1 J of kinetic energy.
10. Calculate the elastic potential energy stored when a 5.0 kg object is set upon a
spring of spring constant 10. N which compresses the spring 0.40 m.
m
11. A 5.0 kg object is pulled across a rough, horizontal floor for 10. m. The coefficient of
kinetic friction between the object and the floor is 0.20.
a. Draw a force
b. Calculate the force of
c. Calculate the energy
diagram of the
friction acting on the
dissipated as the object
is pulled 10. m across
object.
object.
the floor.
© The Physics Classroom, 2009
Energy WS 4
page 3
12. The total mechanical energy of an object is the ______.
a. KE minus the PE of the object
b. PE minus the KE of the object
c. the initial KE plus the initial PE of the object
d. KE plus the PE of the object at any instant during its motion
e. final amount of KE and PE minus the initial amount of KE and PE
13. If an object moves in such a manner as to conserve its total mechanical energy, then
______.
a. the amount of kinetic energy remains the same throughout its motion
b. the amount of potential energy remains the same throughout its motion
c. the amount of both the kinetic and the potential energy remains the same
throughout its motion
d. the sum of the kinetic energy and the potential energy remains the same
throughout its motion
14. Determine the total mechanical energy (TME) of the objects at positions A, B, C and D.
A:
B:
C:
D:
15. Calculate the total mechanical energy (TME) of a 5.2 kg object moving at 2.4 m
positioned 5.8 m above the ground.
© The Physics Classroom, 2009
s
and
Energy WS 4
page 4
Total Mechanical Energy
Important Background: As an object moves, one of the following results must occur.
1. The system’s total mechanical energy is conserved only if there is no friction to
dissipate any energy and there are no external forces (In other words the system
is frictionless and isolated).
2. The total mechanical energy of the system changes when some of the
mechanical energy is dissipated (and is then stored as thermal energy, light
energy, etc.).
3. The system’s total mechanical energy changes due to energy being transferred
into or out of the system by means of an external force (by a process we call
work).
16. Read the following descriptions and indicate whether the objects' kinetic energy,
gravitational potential energy, dissipated energy, and total mechanical energy increases,
decreases or remains the same (=). Also indicate whether there is work done on the
system.
a. A marble begins at an elevated position on top of an inclined ruler and rolls without
sliding down to the bottom of the ruler.
Eg :   
Ek :   
E diss :   
W : yes no
TME :   
b. A marble is rolling along a level table when it hits a note card and slides to a stop.
Eg :   
Ek :   
E diss :   
W : yes no
TME :   
c. A cart is pulled from the bottom of an incline to the top of the incline at a constant
speed. Neglect frictional effects.
Eg :   
Ek :   
E diss :   
W : yes no
TME :   
d. A physics student runs up a staircase at a constant speed.
Eg :   
Ek :   
E diss :   
W : yes no
TME :   
e. A force is applied to a root beer mug to accelerate it from rest across a level
countertop.
Eg :   
Ek :   
E diss :   
W : yes no
TME :   
f. A pendulum bob is released from rest from an elevated position and swings to its
lowest point. Neglect air resistance.
Eg :   
Ek :   
E diss :   
W : yes no
TME :   
g. A car skids from a high speed to a stopping position along a level highway.
Eg :   
Ek :   
E diss :   
W : yes no
TME :   
© The Physics Classroom, 2009
Energy WS 4
page 5
17. Identify the following as being either always true (AT), never true (NT) or might be
true (MBT).
AT, NT, MBT?
Statement:
a. If gravity acts upon an object, then its total mechanical energy
(TME) is conserved.
b. If gravity is the only force acting upon an object and the
system includes both the object and the Earth, then the
system’s total mechanical energy (TME) is conserved.
c.
If sliding friction acts upon an object, then its TME will
decrease.
d. If external forces are doing work upon a frictionless system,
then its TME will be conserved.
e. If there is a net external force acting upon a frictionless
system, then more information is needed to tell if its TME will
be conserved.
f.
If a quantity such as the total mechanical energy is
conserved, then that means that it does not change over the
course of a motion.
18. Consider the three situations below. Begin by identifying the system. Next, identify
whether or not the total mechanical energy (TME) of the system is being conserved.
Then indicate if energy is dissipated during the motion.
System?
System?
System?
TME Conserved?
TME Conserved?
TME Conserved?
Energy dissipated?
Energy dissipated?
Energy dissipated?
© The Physics Classroom, 2009
Energy WS 4
page 6
For each situation, identify the system and then determine whether the total mechanical
energy (TME) of the system is conserved, increases, or decreases.
19. A bungee jumper
rapidly decelerates as
he reaches the end of
his ideal spring-like
bungee cord. Ignore
the effect of air
resistance.
20. A girl releases a
softball from rest from
a height of 2 meters
above the ground; the
ball free-falls to the
ground.
System?
TME
conserved increases
21. A weightlifter briskly
raises a 200-pound
barbell above his
head.
System?
TME
conserved increases
22. A swimmer pushes off
the blocks to
accelerate forward at
the beginning of a
race.
System?
TME
conserved
increases
decreases
decreases
System?
TME
conserved
increases
decreases
decreases
20. A force is applied to a root beer mug to accelerate it across a level counter-top.
System?
a. TME conserved
b. TME increases
c. TME decreases
21. A force is applied to a cart to raise it up an inclined plane at constant speed.
System?
a. TME conserved
b. TME increases
c. TME decreases
22. A marble starts from rest and rolls down an inclined plane. Ignore friction.
System?
a. TME conserved
b. TME increases
c. TME decreases
23. A coffee filter is released from rest and falls with a terminal velocity.
System?
a. TME conserved
b. TME increases
c. TME decreases
24. A car skids to a stop while traveling down a steep hill.
System?
a. TME conserved
b. TME increases
c. TME decreases
25. A pendulum bob is tied to a string and swings back and forth. (Neglect Fair.)
System?
a. TME conserved
b. TME increases
c. TME decreases
© The Physics Classroom, 2009