As a block slides down a frictionless incline, which of the following statements is true（）
A. Both its speed and acceleration increase
B. Its speed and acceleration remain constant
C. Its speed increases and its acceleration remains constant
D. Both its speed and acceleration decrease
E. Its speed increases and its acceleration decreases
F. None of these
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Which of the following is an example of a nonconservative force（）
A. gravity
B. magnetism
C. friction
D. none of the others
A car is going around a racetrack at constant speed. The curves around the track have different radii. In which turn is the magnitude of the car’s acceleration the greatest（）
A. It is the greatest in the turn with the greatest radius
B. It is the greatest in the turn with the smallest radius
C. The acceleration is zero everywhere because of the constant speed
D. More information is needed to determine the answer
E. None of the others
If an object of mass m moves with constant velocity v, the net force on the object is（）
A. mg
B. mv
C. mv/t
D. 0
E. None of these answers is correct
Alex and John are loading identical cabinets onto a truck. Alex lifts his cabinet straight up from theground to the bed of the truck, whereas John slides his cabinet up a rough ramp to the truck. Whic
Alex and John do the same amount of work
B. Alex does more work than John
C. John does more work than Alex
D. None of those statements is necessarily true because the angle of the incline is unknown
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