Work and Energy Quiz
Questions: 16 · 10 minutes
1. Two hikers with equal mass reach the same lookout from the same starting elevation. One takes a steep route and the other a longer winding route. Ignoring friction, how does the work done by gravity compare?
Gravity does the same work on both routes
Gravity does more work on the winding route
Gravity does more work on the steep route
Gravity does zero work on both routes
2. Which expression gives the elastic potential energy stored in an ideal spring with spring constant k when it is stretched a distance x from equilibrium?
The spring constant multiplied by the extension
The spring constant multiplied by the extension squared
One-half multiplied by the mass and the speed squared
One-half multiplied by the spring constant and the extension squared
3. A 2 kg ball moves at 3 m/s. What is its kinetic energy?
9 J
6 J
12 J
18 J
4. A sled slides forward across rough, level ground and gradually slows. Which force does negative work on the sled?
The sled's weight
The ground's normal force
The sled's forward velocity
Kinetic friction
5. Under which condition is total mechanical energy, defined as kinetic plus potential energy, conserved?
Whenever the object's speed is constant
Only when gravitational potential energy is zero
Whenever an object moves in a straight line
When only conservative forces do work and no non-conservative external work transfers energy
6. A motor transfers 600 J of energy in 3 seconds at a steady rate. What is its power output?
1,800 W
603 W
200 W
0.005 W
7. Near Earth's surface, which expression gives the change in gravitational potential energy when a mass m rises through a vertical height h?
One-half times mass times speed squared
Force multiplied by displacement
One-half times spring constant times height squared
Mass times gravitational field strength times height
8. According to the work–energy theorem, the net work done on an object equals what quantity?
Its final kinetic energy
Its change in kinetic energy
Its total mechanical energy
Its change in momentum
9. A person carries a suitcase horizontally at constant height. The upward support force is perpendicular to the suitcase's horizontal displacement. How much work does that support force do?
Zero work
Positive work equal to force times distance
Negative work equal to force times distance
Work equal to the suitcase's weight
10. A constant force of magnitude F pulls an object through distance d at an angle θ to the displacement. Which calculation gives the work done by that force?
Multiply F and d by the sine of θ
Multiply F and d by the tangent of θ
Multiply F and d by the cosine of θ
Multiply F by d, then divide by the cosine of θ
11. A constant 20 N horizontal force moves a box 3 m in the same direction as the force. How much work does the force do?
60 J
23 J
17 J
6.7 J
12. On the same level road, a car brakes with the same constant friction force in two trials. If its initial speed is doubled, how does the stopping distance change?
It stays the same
It becomes four times as long
It triples
It doubles
13. A worker pushes a crate across a level floor at constant speed. The push and friction are the only horizontal forces. What is the net work done on the crate?
It is positive because the crate moves forward
It is zero because the crate's kinetic energy does not change
It is negative because friction acts on the crate
It equals the work done by the worker alone
14. A roller-coaster car descends a frictionless track. What happens as its height decreases?
Gravitational potential energy increases while kinetic energy decreases
Both gravitational potential energy and kinetic energy decrease
Gravitational potential energy decreases while kinetic energy increases
Both gravitational potential energy and kinetic energy remain constant
15. What is the SI unit of work and energy?
Newton
Watt
Joule
Pascal
16. Two identical carts move at speeds v and 2v. How does the kinetic energy of the faster cart compare with that of the slower cart?
It is twice as large
It is four times as large
It is three times as large
It is unchanged