Work and Energy Test -- HONORS
Multiple Choice. Darken the letter of your response on the answer sheet.
_____ 1.) Work is measured in ____
A.) kgm/s
B.) Newtons
C.) Joules
D.) none of the above
_____ 2.) Energy is best described as ____
A.) the ability to do work
B.) the net force on an object
C.) frictional efficiency
D.) none of these
_____ 3.) True or false. An object that is not moving has no kinetic energy.
A.) True because if it has a speed of zero, its KE is also zero
B.) False because the object still has inertia
Suppose an arrow is placed into a bow (Figure 1). The arrow is then drawn back against
the force of the bowstring and held in place (Figure 2). The archer, the person using the
bow, then releases the arrow. The arrow rubs against the bow for a short time (friction is
applied) as the arrow is sent toward a target. (Figure 3)
Figure 1
Figure 2
Figure 3
Now answer these true or false questions. Mark “A” for “true”; mark “B” for “false.”
____
____
____
____
____
4.)
5.)
6.)
7.)
8.)
Work is done as the string is being pulled back.
After drawing the arrow back, the bow and arrow have potential energy.
As the arrow is held in place, the archer is doing work.
As the arrow is released, potential energy becomes kinetic energy.
The KE of the arrow after releasing is larger than the PE it had just
before releasing it.
____ 9.) The KE of the arrow after releasing it is exactly equal to the PE it had just
before releasing it, even though there was friction on the arrow.
____ 10.) The total amount of energy of the bow and arrow system remains the same.
_____ 11.) Potential energy can describe all of the following except ____.
A.) The stored energy in a compressed spring
B.) The stored energy of a 5 N weight raised 2 m
C.) The energy that a 100 kg rock has after rolling down a hill to level ground
D.) The energy that a 100 kg rock has at the top of a hill
_____ 12.) Which object has the most kinetic energy?
A.) A 20 kg wagon moving 20 m/s
B.) A 10 kg wagon moving 20 m/s
C.) A 20 kg wagon moving 30 m/s
D.) A 10 kg wagon moving 30 m/s
____ 13.) Suppose a notebook is tossed on to a desk. The notebook lands on the desk
and slides for a little before coming to a stop. The kinetic energy that the
sliding notebook once had ____.
A.) transformed into heat energy
B.) disappeared
C.) transformed into efficiency
D.) became power
_____ 14.)
A.)
B.)
C.)
D.)
As a sled slides down a snowy hill ____.
it loses kinetic and gains potential energy
it looses both potential and kinetic energy
it gains kinetic but loses potential energy
it gains both potential and kinetic energy
____ 15.) Among the following, the one that would require the most work is ____.
A.) lifting a 10 pound object 6 feet
B.) lifting a 20 pound object 6 feet
C.) lifting a 10 pound object 3 feet
D.) lifting a 20 pound object 3 feet
____ 16.) Power is ____.
A.) the time it takes you to do something
B.) the amount of work done when something is moved
C.) the rate of doing work
D.) the amount of efficiency during an energy transformation.
____ 17.) Suppose a toy car at the top of a ramp has 2 J of GPE (gravitational potential
energy). It is then released and allowed to roll down the ramp. If the energy
transformation is 50% efficient, then the car will have ____ of KE at the
bottom of the ramp.
A.) 0 Joules
B.) 4 J
C.) 1.5 J
D.) 1 J
____ 18.) A toy car is raised to the top of an inclined track. It is released from rest and
allowed to roll down. The efficiency of this transformation would be found by
____.
A.) dividing the height by the weight of the car
B.) multiplying the speed of the car by the height from which it was released
C.) dividing the KE it had at the bottom of the ramp by the PE it had at the top
D.) dividing the PE it had at the top of the ramp by the KE it had at the bottom
____19.) A bowling ball rolls along the track of a ball-return, back toward the players.
As it reaches the end of the ball-return, the bowling ball rolls up a ramp.
To say that “the energy of the ball is conserved” means that ____.
A.) the PE is exactly equal to the KE of the ball at any time
B.) the PE gained by the ball as it rolls up the ramp gets transformed
C.) the KE lost by the ball as it rolls up the ramp transforms into PE and heat
D.) the KE of the ball stays constant – it never decreases nor increases
____ 20.) Jack is 100 kg and Jill is 50 kg. Both run up a hill, together, and get to the top
in the same amount of time.
Among the following, which one is known to be true?
A.) Jill did more work in getting to the top of the hill.
B.) Jack and Jill did the same amount of work in climbing the hill.
C.) Jack had a greater power in climbing the hill than Jill did.
D.) Jill had a greater power in climbing the hill than Jack did.
Part 2. Problems.
W=Fd
eff = Eout / Ein
GPE = mgh = Fwh
KE = ½ mv2
P=W/t
A 400 N child climbs to the top of a slide in 8 seconds. The height of the climb is
2.0 meters. He slides down and 100 Joules are “lost” as heat energy during the
slide. Answer the following problems based on this.
21.)
Find the work done in climbing the slide.
A.) 800 J
B.) 400 J
C.) 200 J
D.) 100 J
22.)
Find the power in climbing up the slide.
A.) 200 W
B.) 100 W
C.) 50 W
D.) 20 W
23.)
Find the KE at the bottom of the slide. This is the GPE minus the energy lost as
heat.
A.) 700 J
B.) 300 J
C.) 100 J
D.) 0 J
24.)
Find the efficiency of the energy transformation. This is the energy the child has
at the bottom of the slide divided by the energy he has at the top.
A.) 0.875
B.) 0.250
C.) 0.125
D.) 0.500
25.)
Suppose the same child went down that same slide. But this time, there were
only 50 Joules lost due to the heat generated during the slide. Which of the
following statements is most accurate regarding this?
A.) The child had more GPE at the top of the slide this time.
B.) The energy transformation has a higher efficiency this time
C.) Energy is not conserved.
D.) The child must have climbed the slide with a greater power.
W=Fd
eff = Eout / Ein
GPE = mgh = Fwh
KE = ½ mv2
P=W/t
A 5 kg ball is suspended by a cable from the ceiling.
As it hangs still, it has a height of zero meters.
A student pushes on the ball so that the ball is
raised to a position that is 0.40 m higher than
it had been, originally.
The ball is held in this position.
0.4 m
26.) Determine the work done in raising the ball to this position.
A.) 19.6 J
B.) 10 J
C.) 4.9 J
D.) 2 J
27.) The ball is released. Assuming the efficiency of the transformation of GPE to KE is
0.90, determine the speed the ball will have at the bottom of the swing (where it is
again at a height of zero meters).
A.) 0.63 m/s
B.) 2.66 m/s
C.) 1.98 m/s
D.) 2.80 m/s
A block whose mass is 4 kg is sliding along
a horizontal frictionless surface with a speed
of 1.6 m/s. It then encounters a rough surface
where the frictional force on the block is 12 N.
The block, therefore, skids to a stop in a distance, d.
d
28.) Determine the kinetic energy of the block as it moves along the frictionless surface.
A.) 39.2 J
B.) 10.24 J
C.) 5.12 J
D.) 3.2 J
29.) Determine the work done by friction in stopping the block.
A.) 39.2 J
B.) 10.24 J
C.) 5.12 J
D.) 3.2 J
30.) Determine the distance, d, that the block skids on the rough surface.
A.) 3.27 m
B.) 0.85 m
C.) 0.43 m
D.) 0.26 m
Work and Energy Test
Honors