Chapter 9, Problem 34PQ

(a)

To determine

Whether work done is positive, negative, or zero.

(b)

To determine

Whether work done is positive, negative, or zero, when a man moves a child in a stroller across a frictionless floor so that the man and child glide together at a constant speed.

(c)

To determine

Whether work done is positive, negative, or zero, when a man prevents a child in a stroller from accelerating as it travels downhill.

(d)

To determine

Whether work done is positive, negative, or zero, when a man pushes the Great Wall of China, yet it remains motionless.