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How much total work does gravity do on you as you climb a mountain and descend to your starting point? Given this result, why do you feel so tired when you return from such a hike?

A car rounds a circular curve while its speed decreases. Is the net work done on the car positive, zero, or negative? Explain.

Give an example of how the word "work" used in casual conversation differs from its meaning in physics.

A factory worker pushes hard against a heavy toolbox to keep it at rest on a ramp. Is he doing work?

A nonzero net force is applied to an object, but its kinetic energy doesn't change. Explain why the force must be perpendicular to the object's velocity.

If an object's speed triples, by what factor does its kinetic energy increase?

You drag a box \(2 \mathrm{~m}\) across the floor at constant speed. Next, you drag the same box \(2 \mathrm{~m}\) across the same floor, giving it constant acceleration. Compare the work done by kinetic friction in the two cases.

Lift a hammer a fixed distance at constant velocity. Next, lift the same hammer the same distance with a constant upward acceleration. Compare the work you do in the two cases.

Is rolling friction a conservative or nonconservative force?

You launch two projectiles off a cliff at the same speed, one \(30^{\circ}\) above the horizontal, the other \(30^{\circ}\) below. Ignoring air resistance, compare their speeds when they hit the ground. Repeat, accounting for air resistance.