Does an object's speed at the bottom of a frictionless ramp depend on the shape of the ramp or just on its height? Explain. What if the ramp is not frictionless?

An advertisement for a portable electrical generating unit claims that the unit's diesel engine produces $28,000 \mathrm{hp}$ to drive an electrical generator that produces $30 \mathrm{MW}$ of electrical power. Is this possible? Explain.

When you jump from the ground into the air, where does your kinetic energy come from? What force does work on you to lift you into the air? Could you jump if you were floating in outer space?

A compressed spring is clamped in its compressed position and then is dissolved in acid. What becomes of its potential energy ?

If a projectile is fired upward at various angles above the horizontal, it has the same initial kinetic energy in each case. Why does it not then rise to the same maximum height in each case?

The sign of many physical quantities depends on the choice of coordinates. For example, a y for free-fall motion can be negative or positive, depending on whether we choose upward or downward as positive. Is the same true of work? In other words, can we make positive work negative by a different choice of coordinates? Explain.

An elevator is hoisted by its cables at constant speed. Is the total work done on the elevator positive, negative, or zero? Explain.

Can the $\textit{total}$ work done on an object during a displace- ment be negative? Explain. If the total work is negative, can its magnitude be larger than the initial kinetic energy of the object? Explain.

A rope tied to a body is pulled, causing the body to accelerate. But according to Newton’s third law, the body pulls back on the rope with a force of equal magnitude and opposite direction. Is the total work done then zero? If so, how can the body’s kinetic energy change? Explain.

A woman bounces on a trampoline, going a little higher with each bounce. Justify how she increases the total mechanical energy.

A person on a trampoline can go higher with each bounce. How is this possible? Is there a maximum height to which the person can go?

When you use a jack to lift a car, the force you exert on the jack is much less than the weight of the car. Does this mean that less work is done on the car than if the car were lifted directly?

True or false? If hydrogen molecules and oxygen molecules have the same kinetic energy, then they have the same speed. Explain your answer.

How does a lettuce spinner remove water from lettuce?