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11. Velocity is known as a vector quantity. What does this tell us about velocity?

a. Velocity will always be positive.

b. Velocity is instantaneous.

c. Velocity will have size and direction.

d. Velocity is the same as acceleration.

12. Which of the following statements best explains the key difference between velocity and speed?

a. Velocity must be reported in m/s, but speed can have other distance time units.

b. Velocity depends on direction; speed does not.

c. Objects can have different speeds if they are moving with the same velocities, but not different velocities if they are moving with the same speeds.

d. Due to Earth's gravity, an object's velocity will always be slightly larger than its speed.

13. If a rock slips off a cliff, and after 5.0 seconds it reaches a speed of 49 m/s, what is the average acceleration for the falling rock?

a. 245 mm/s2

b. 9.8 m/s

c. 9.8 m/s2

d. 9.8 m

14. Which of the following describes terminal velocity?

a. when air resistance forces = friction of a falling object

b. when air resistance forces = velocity of the falling object

c. when air resistance forces = sliding friction of a falling object

d. when air resistance forces = gravitational forces of a falling object

15. Plotting a graph of the distance covered by a moving object on the y-axis and the time required to cover that distance at several intervals on the x-axis produces a slope with an upward direction. What does the slope represent?

a. average speed

b. average acceleration

c. average friction

d. instantaneous speed

16. Acceleration is measured in which units?

a. s/km2

b. m/s2

c. cm/s

d. km/h

17. Speed can be defined as

a. distance/time.

b. velocity/time.

c. displacement/time.

d. acceleration/time.

18. The force that opposes the sliding motion of two surfaces that are in contact is

a. air resistance.

b. friction.

c. inertia.

d. net force.

19. Which of the following statements about an object in free fall is true?

a. Its momentum is constant.

b. It has no inertia.

c. It pulls on Earth and Earth pulls on it.

d. Its acceleration depends on its mass.

20. Suppose a baseball player hits a 0.25 kg ball with a bat that causes the ball's acceleration to be 4000 m/s2. What is the net force applied to the ball?

a. 16000 N

b. 1000 N

c. –16000 N

d. –1000 N

21. The planet Jupiter is more massive than Earth. What is the weight of a 75 N person on Jupiter if the acceleration due to gravity is approximately 2.5 times greater than on Earth?

a. The mass of Jupiter is needed to solve this problem.

b. 30 Kg

c. 190 N

d. 30 N

22. Which of the following statements is not true?

a. The gravitational force of Earth helps keep the Moon in orbit around Earth.

b. As it moves around Earth, the Moon's velocity is changing.

c. As it moves around Earth, the Moon's inertia keeps it moving in a curved path.

d. Centripetal force keeps the Moon moving in a curved path around Earth.

23. Given that two people are walking at the same speed, 0.70 m/s, but one has a mass of 70 kg and the other has a mass of 63 kg, which of the following statements is accurate?

a. The 70 kg person will have a momentum of 100 kg/m/s.

b. The 70 kg person will have less momentum than the 63 kg person.

c. The momentum of the 63 kg person will be 93 kg/m/s.

d. The 63 kg person will have about 90% of the momentum of the 70 kg person.

24. According to Newton's third law of reaction and action it would seem that a spacecraft could not move because as it burns fuel the molecules exit with a force but then encounter a vacuum in space. How is the necessary unbalanced force generated in space?

a. The gravity of the Sun never reaches zero, even over long ranges, and this acts as the reaction force.

b. The molecules of exiting gas, even though small, provide enough of a reaction force on the spacecraft to move it forward.

c. Newton's laws were developed on Earth for earthbound systems. They do not apply in space. Heat powers the spacecraft to move it forward.

d. In space, the concepts of up, down, forward, reverse are just choices. The rocket is moving so it does not need a reaction to move it forward.

25. The amount of force that is needed to change an objects motion is its

a. velocity.

b. acceleration.

c. mass.

d. momentum.

26. The energy a moving object has because of its motion is called

a. kinetic energy.

b. potential energy.

c. elastic energy.

d. gravitational energy.

27. Which answer best describes energy transformation?

a. Mechanical energy is lost.

b. Mass is convert