Question

A block slides down a frictionless inclined plane. All of the following are correct except for
A. the velocity of the block changes with time.
B. the normal force on the bloc changes with time.
C. the acceleration of the block is less than the acceleration of gravity.
D. the normal force on the block is less than the weight of the block.
E. work done by the normal force is zero.

A heavy suitcase is carried by a porter down a flight of stairs. The work done on the suitcase by the
Earth’s gravity is
A. zero
B. positive
C. negative
D. unknown; more information on the slope of the stairs is needed to work out the answer.
E. unknown; more information on the height of the stairs is needed to work out the answer.

Answer 1