PHYS 1114 Chapter 6 Misconceptual Questions

A car accelerates from rest to 30 km/h. Later, on a highway it accelerates from 30 km/h to 60 km/h. Which takes more energy: going from 0 to 30 or from 30 to 60?

30 to 60

When the speed of your car is doubled, by what factor does its kinetic energy increase?

4

A traveling car at velocity v can stop in a minimum distance d. What would be the car's minimum stopping distance if it were traveling at a velocity of 2v?

4d

Two balls are thrown off of a building with the same speed, one straight up and one at a 45° angle. Which statement is true if air resistance can be ignored?

Both hit the ground with the same speed.

A ball is thrown straight up. At what point does the ball have the most energy? Ignore air resistance.

Everywhere. The energy of the ball is the same at all of these points.

A bowling ball is dropped from a height h onto the center of a trampoline, which launches the ball back up into the air. How high will the ball rise?

No more than h - probably a little less.

A satellite in circular orbit around the Earth moves at constant speed. This orbit is maintained by the force of gravity between the Earth and the satellite, yet no work is done on the satellite. How is this possible?

No work is done if the direction of motion is perpendicular to the force.

You push a heavy crate down a ramp at a constant velocity. Only four forces act on the crate. Which force does the greatest magnitude of work on the crate?

The force of friction.

A ball is thrown straight up. Neglecting air resistance, which statement is NOT true regarding the energy of the ball?

The potential energy decreases while the ball is going up.

Engines, including car engines, are rated in horsepower. What is horsepower?

The rate at which the engine can do work?

Assuming that there is a small amount of friction on the hill which the skier skis, which hill will he have the highest speed at the bottom of?

The tallest hill with the steepest slope

A skier starts from rest at the top of each of the hills. On which hill will the skier have the highest speed at the bottom if we ignore friction?

The tallest hills, no matter how steep

A man pushes a block up an incline at a constant speed. As the block moves up the incline...

its potential energy increases and its kinetic energy stays the same.

You push very hard on a heavy desk, trying to move it. You do work on the desk...

only if it starts moving