Reading Quiz Unit 3 Study Set (Ch9II - Ch6)

Which of the following forces are conservative forces:

- the force of gravity - elastic force of a spring

Suppose you lift a suitcase from the floor to a table. The work you do on the suitcase depends on which of the following:

- the height of the table - the weight of the suitcase

A rubber band is stretched by 1.0 cm when a force of 0.35 N is applied to each end. If instead a force of 0.70 N is applied to each end, estimate how far the rubber band will stretch from its unstretched length:

2.0 cm

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 km/h

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

4

A car traveling at a 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 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.

It is possible to do work on an object that remains at rest. T/F

False

Kinetic energy can be negative. T/F

False

A parking garage is designed for two levels of cars. To make more money, the owner decides to double the size of the garage in each dimension (length, width, and number of levels). For the support columns to hold up four floors instead of two, how should he change the columns' diameter?

Increase the area of the columns by a factor of 8 by increasing their diameter by a factor of 2sqrt2

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.

As you increase the force that you apply while pulling on a rope, which of the following is NOT affected?

The Young's modulus of the rope.

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.

Potential energy can sometimes be negative. T/F

True

Two steel wires have the same length and are under the same tension. But wire A has twice the diameter of wire B. Which of the following is true?

Wire B stretches four times as much as wire A.

A skier starts from rest at the top of each of the hills shown in Fig. 6-34. On which hill will the skier have the highest speed at the bottom if we ignore friction:

c and d equally

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 remains the same.

A woman is balancing on a high wire which is tightly strung, as shown in Fig. 9-45. The tension in the wire is

much more than the woman's weight.

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

only if it starts moving.