12. A student releases a ball from rest on an inclined plane and measures that i
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Question
12. A student releases a ball from rest on an inclined plane and measures that it travels a distance of 0.5 m in a time of 2.0 s. The average speed of the ball is:
A. 0.25 m/s.
B. 2.0 m/s.
C. 0.5 m/s.
D. 1.0 m/s.
13. A car starts from rest and reaches 20 m/s in 10 seconds. The average acceleration of the car in m/s2 is:
A. 4.0
B. 2.0
C. 10.0
D. Zero
E. 1.0
14. A quantity that is a measure of how the velocity of a body changes with time is:
A. Acceleration.
B. Momentum.
C. Speed.
D. Displacement.
15. The acceleration of a body must be zero at a point where:
A. the instantaneous velocity is not zero but changing.
B. the instantaneous velocity is zero but changing.
C. the instantaneous velocity is constant.
16. Suppose a graph of displacement of a body versus time is constructed. The slope of the graph at any point may be identified with:
A.instantaneous acceleration.
B. instantaneous velocity.
C. average speed.
D. average acceleration.
17. A car rolls down an incline starting from rest. A graph of position versus time is made for this motion. One can get the:
A. velocity from the area under the graph.
B. instantaneous velocity from the slope of the graph.
C. distance traveled from the slope of the graph.
D. acceleration from the area under the graph.
E. acceleration from the slope of the graph.
18. Which of the following is not an appropriate unit for measuring acceleration?
A. m/s
B. km/min/s
C. m/min2
D. miles/hr/s
E. ft/s2
19. A driver of a car steps on the brakes, causing the velocity of the car to decrease. According to the definition of acceleration provided in this chapter, does the car accelerate in this process? Explain.
A. Yes, acceleration is the change in velocity per unit time, whether that change is positive or negative.
B. No, the car is not increasing in velocity over an interval of time.
C. There is not enough information to determine whether or not the car is accelerating.
20. The tendency of an auto to maintain its velocity is called:
A. inertia.
B. speed.
C. mass.
D. momentum.
7. The highway patrol sometimes uses radar guns to identify possible speeders and at other times uses associates in airplanes who note the time taken for a car to pass between two marks some distance apart on the highway. What do each of these methods measure, average speed or instantaneous speed?
A. Only the radar gun measures instantaneous speed.
B. Both methods measure instantaneous speed.
C. Both methods measure average speed.
D. Only the airplane measures instantaneous speed.
Can you think of situations in which either one of these methods might unfairly penalize a driver? Explain
Explanation / Answer
14)A.acceleartion
15)C. the instantaneous velocity is constant.
16)B. instantaneous velocity.
17)B. instantaneous velocity from the slope of the graph
18)A. m/s
19)A. Yes, acceleration is the change in velocity per unit time, whether that change is positive or negative.
20)A. inertia.
7)A. Only the radar gun measures instantaneous speed.
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