# Student

Pages: 7 (1740 mots) Publié le: 16 avril 2011
1. question t3-1
(Points: 1)     Kinetic energy is defined to be one-half the

1. speed
2. velocity
3. mass times the speed squared
4. mass times the acceleration
5. none of above
2. question t3-2
(Points: 1)     When a star undergoes a supernova explosion, the total energy of the universe

1. increase
2. decrease
3. no change
4. increase all the time
5. none ofabove
3. question t3-3
(Points: 1)     Which has the greater kinetic energy, a heavy truck at rest or a moving roller skate?

1. the heavy truck
2. the roller skate
3. The kinetic energies are equal.
4. heavy truck always has greater kinetic energy.
5. none of above
4. question t3-4
(Points: 1)     If a sports car with a mass of 1000 kg travelsdown the road with a speed of 20 m/s, its kinetic energy is 200,000

1. kg/(m/s)2
2. kg•s2/m2
3. kg•m/s
4. kg•m2/s2
5. none of above
5. question t3-5
(Points: 1)     A sports car with a mass of 1000 kg travels down the road with a speed of 20 m/s. Which is larger, its momentum or its kinetic energy?

1. momentum
2. kinetic energy
3. They are equal.
4. The two cannot becompared
5. none of above
6. question t3-6
(Points: 1)     What is the kinetic energy of an 80-kg sprinter running at 10 m/s?

1. 40000 J
2. 4000 J
3. 8000 J
4. 10000 J
5. 60000 J
7. question t3-7
(Points: 1)     Assume that a red car has a mass of 4000 kg and a white car has a mass of 2000 kg. If both cars are traveling at the same velocity,1. their kinetic energies are equal.
2. their momenta are equal.
3. the red car's kinetic energy is twice as big.
4. the white car's kinetic energy is twice as big
5. none of above
8. question t3-8
(Points: 1)     Assume that two cars have the same mass, but that the blue car has half the speed of the red car. We then know that the red car has ____ kinetic energy as theblue car

1. twice as much
2. one half as much
3. four times as much
4. one fourth as much
5. none of above
9. question t3-9
(Points: 1)     Under what conditions is the kinetic energy conserved in a collision?

1. It is always conserved.
2. When the collision is totally elastic.
3. When there is no net outside force
4. When there is no friction.
5. none of above
10. question t3-101
(Points: 1)     A 3-kg toy car with a speed of 6 m/s collides head-on with a 2-kg car traveling in the opposite direction with a speed of 4 m/s. If the cars are locked together after the collision with a speed of 1 m/s, how much kinetic energy is lost?

1. 67.5 J
2. 75.5 J
3. 20 J
4. 90 J
5. 40.5 J
11. question t3-11
(Points: 1)    In physics, work is defined as the product of the

1. net force and the distance traveled.
2. net force parallel to the motion and the distance traveled
3. net force parallel to the motion and the time it is applied
4. applied force and the distance traveled.
5. none of above
12. question t3-12
(Points: 1)     Two objects have different masses but the same kineticenergies. If you stop them with the same retarding force, which one will stop in the shorter distance?

1. the heavier one
2. the lighter one
3. Both stop in the same distance.
4. it is hard to tell
5. none of above
13. question t3-13
(Points: 1)     The kinetic energy of an object moving in a circle at a constant speed is

1. continually changing as the force changesdirection
2. equal to the force times the time for one revolution
3. equal to one half of the potential energy.
4. constant.
5. none of above
14. question t3-14
(Points: 1)     A bowler lifts a bowling ball from the floor and places it on a rack. If you know the weight of the ball, what else must you know in order to calculate the work she does on the ball?

1. the mass of...

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