Name _________________________________________
Work Energy Theorem Practice
Date __________________
1. An 8000. Kg aircraft is taxiing for takeoff, and moving at 20.0 m/s when the
pilot notices that there is only 100.0 m of runway space left. She, therefore,
increases the engines’ thrust. What minimum thrust (force) will be required
to allow the jet to achieve its take-off speed of 70 m/s?
2. A 1300. Kg car is moving to the right at 30.0 m/s when the driver applies the
brakes, which apply a stopping force of 8.1 x 103 N. If the brakes are applied
over a distance of 68.0 m, what will be the final speed?
3. Calculate the following:
a. When a hockey player makes a wrist shot, he applies a reasonably
constant force to a puck for a distance of between 0.8 to 1.4 m. (That
is, the puck is in contact with the stick through such a short distance
as the stick swings along the ice). Explain why the work energy
theorem may be used to analyze the resulting motion of the puck.
b. It would be reasonable to assume that a hockey player, using the stick,
is able to exert a force of 60.0 N on a puck for a distance of 1.00 m. The
mass of a puck is approximately 0.200 kg. Determine:
(i) The amount of work done on the puck.
(ii) The amount of kinetic energy in the puck immediately after
release.
(iii) The final speed of the puck. Check to ensure that the answer is
reasonable!
LPPACS – Schmidt
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Name _________________________________________
Work Energy Theorem Practice
Date __________________
4. Assuming no friction losses, what will be the kinetic energy of the arrow
when it leaves the bow? (The force shown is the average force).
5. A 1.0 kg piece of ice is sliding along a frozen pond at 10.0 m/s.
a. What will be the CHANGE in its kinetic energy if a force of 5.0 N acts
on it for a distance of 2.0 m?
b. What will be the final speed of the piece of ice?
6. A hockey puck is accelerated, using a hockey stick, over a smooth, level ice
surface. The puck has a mass of 0.400 kg and is moved by the stick for a
distance of 0.800 m. What was the average force applied to the puck if the
final speed is 25.0 m/s? If the stick is in contact with the puck for 0.12 s,
how much power was exerted on the puck?
LPPACS – Schmidt
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Name _________________________________________
Work Energy Theorem Practice
Date __________________
7. How much work is done on a car with a mass of 1520 kg if it starts from rest
and it reaches a speed of 25.0 m/s? Assume that friction is negligible.
8. The dynamics cart in the picture was pushed by a spring as it extended by a
distance of 8.55 cm. The cart has a mass of 1.20 kg and reaches a final speed
of 2.91 m/s. Calculate the average force applied by the spring.
9. A steam catapult apples a very large force to supplement the engine thrust of
a jet fighter as it takes off from an aircraft carrier. The jet has a mass of 4000
kg and must reach its take off speed of 70 m/s at the end of the 220 m flight
deck. What is the net force of the catapult and engines?
LPPACS – Schmidt
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Name _________________________________________
Work Energy Theorem Practice
Date __________________
10. Do the following:
a. A force of 4.40 N is applied to a dart over a distance of 54 cm. The dart
has a mass of 28 g. Assuming no energy is lost due to friction, what
will be the kinetic energy of the dart after it is thrown?
b. Use your result in part a) to calculate the speed of the dart.
11. A skater with a mass of 70.0 kg is moving across a frictionless ice surface at
4.82 m/s. If the skater brakes and applies an average force of 60.0 N in order
to stop, what will be the skater's stopping distance?
12. A 22 kg penguin slides down a frictionless ice ramp that makes an angle of
35° with the horizontal. How much work is done on the penguin by the force
of gravity if it slides for 8.8 m? How much power is produced if the penguin
slides for 3.4 seconds?
LPPACS – Schmidt
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