Questions from Modern Physics

Q: Students sometimes say that the force of gravity on an object is

Students sometimes say that the force of gravity on an object is 9.8 m/s2. What is wrong with this view?

Q: Why is the earth only approximately an inertial reference frame?

Why is the earth only approximately an inertial reference frame?

Q: Time yourself while running up a flight of steps, and compute

Time yourself while running up a flight of steps, and compute the average rate at which you do work against the force of gravity. Express your answer in watts and in horsepower.

Q: The centrifugal force is not included in the free-body diagrams

The centrifugal force is not included in the free-body diagrams of Figs. 5.34b and 5.35. Explain why not. Figs. 5.34b: Figs. 5.35b:

Q: A professor swings a rubber stopper in a horizontal circle on the

A professor swings a rubber stopper in a horizontal circle on the end of a string in front of his class. He tells Caroline, in the front row, that he is going to let the string go when the stopper is...

Q: To keep the forces on the riders within allowable limits, many

To keep the forces on the riders within allowable limits, many loop-the-loop roller coaster rides are designed so that the loop is not a perfect circle but instead has a larger radius of curvature at...

Q: An advertisement for a portable electrical generating unit claims that the unit’s

An advertisement for a portable electrical generating unit claims that the unit’s diesel engine produces 28,000 hp to drive an electrical generator that produces 30 MW of electrical power. Is this pos...

Q: A car speeds up while the engine delivers constant power. Is

A car speeds up while the engine delivers constant power. Is the acceleration greater at the beginning of this process or at the end? Explain.

Q: Which feels a greater pull due to the earth’s gravity: a

Which feels a greater pull due to the earth’s gravity: a 10-kg stone or a 20-kg stone? If you drop the two stones, why doesn’t the 20-kg stone fall with twice the acceleration of the 10-kg stone? Expl...

Q: Why is it incorrect to say that 1.0 kg equals

Why is it incorrect to say that 1.0 kg equals 2.2 lb?