hw 3

A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater acceleration. speed. momentum. all of the above none of the above

momentum.

A 1-kg ball dropped from a height of 2 m rebounds only 1.5 m after hitting the ground. The amount of energy converted to heat is about 1.5 J. 1.0 J. more than 2.0 J. 2.0 J. 0.5 J.

more than 2.0 J.

A boulder is dropped onto mud and plows into it a certain distance. If it hits with three times as much speed, the distance it plows into the mud will likely be more than three times as deep. twice as deep. the same distance. three times as deep.

more than three times as deep.

A cat and a mouse run along a road with the same kinetic energy. The faster runner is the cat. mouse. both run at the same speed not enough information

mouse.

F =

mv/t

With no air resistance a projectile fired horizontally maintains its horizontal component of velocity because no forces act on it. of no initial vertical component of velocity. no horizontal forces act on it. all of the above none of the above

no horizontal forces act on it.

If you push for an hour against a stationary wall, you do no work on the wall. at all. both of these none of the above

on the wall.

The period of a satellite, the time it takes for a complete revolution, depends on the satellite's weight. mass. radial distance. all the above none of the above

radial distance.

Consider a gun with a pellet that is more massive than the gun. The firing speed is greater for the pellet. recoiling gun. both are the same none of the above

recoiling gun

Weight can be simulated in a space vehicle if the vehicle is in a circular orbit about Earth. falling. rotating. none of the above

rotating.

Two billiard balls having the same mass roll toward each other at the same speed. What is the net momentum of the two-ball system? 10 kg•m/s 0 kg•m/s not enough information

0 kg•m/s

If a projectile is fired straight up at a speed of 10 m/s, neglecting air resistance, the time it takes to reach the top of its path is 2 s. 1 s. 10 s. not enough information

1 s.

What is the mass of a ball moving at 4 m/s with a momentum of 48 kg∙m/s? 192 kg 12 kg 48 kg 4 kg none of the above

12 kg

A car moves 4 times as fast as another identical car. Compared with the slower car, the faster car has 8 times the kinetic energy. 12 times the kinetic energy. 4 times the kinetic energy. 16 times the kinetic energy.

16 times the kinetic energy.

A shopping cart moves with a kinetic energy of 40 J. If it moves at twice the speed, its kinetic energy is 80 J. 160 J. 40 J. not enough information

160 J.

When the input piston of a hydraulic press is depressed 20 cm, the output piston is observed to move 1 cm. An input force of 1 N can raise no more than 21 N. 20 N. 1 N. 10 N.

20 N.

A 2500-N pile driver ram falls 10 m and drives a post 0.1 m into the ground. The average force on the post is 250,000 N. 2500 N. 2,500,000 N. 25,000 N.

250,000 N.

What is the speed of a 4-kg ball with a momentum of 12 kg∙m/s? 3 m/s 4 m/s 12 m/s 48 m/s none of the above

3 m/s

A 5000-kg freight car crashes into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg freight car? 4 m/s 6 m/s 5 m/s 8 m/s none of the above

6 m/s

The most energy per unit mass can be extracted from coal. natural gas. uranium. petroleum.

uranium.

The force of a falling apple hitting the ground depends upon the time of contact with the ground. the speed of the apple just before it hits the ground. whether or not the apple bounces. all of the above

all of the above

If the Sun were twice as massive, its pull on the Earth would double. Earth's pull on the Sun would double. both of these none of the above

both of these

While driving down the highway a lovebug spatters onto your windshield. Which undergoes the greater change in momentum during the time of contact? your car the lovebug both the same

both the same

work formula

force (distance)

Two identical arrows, one with twice the speed of the other are fired into a bale of hay. The faster arrow will penetrate the bale four times as far as the slower arrow. the same distance as the slower arrow. more than four times as far as the slower arrow. twice as far as the slower arrow. none of the above

four times as far as the slower arrow.

A heavy truck and a small car roll down a hill at the same speed and need to stop in the same amount of time. Compared with the force to stop the car, the force needed to stop the truck is greater. smaller. the same.

greater.

The speed of a bullet fired from a gun will be about the same as the speed of the recoiling gun because velocity is conserved. when momentum is conserved. if the masses of the bullet and gun are equal. when both velocity and momentum are conserved. none of the above

if the masses of the bullet and gun are equal.

When the distance between a pair of stars decreases by half, the force between them decreases by one-quarter. increases to four times as much. decreases by one-half. increases to twice as much. stays the same.

increases to four times as much.

If a charging rhinoceros has momentum, it must also have potential energy. work. kinetic energy. all of the above

kinetic energy.

According to Newton, the greater the distance between gravitationally interacting objects, the constancy of the force between them. less the gravitational force between them. more the gravitational force between them.

less the gravitational force between them.

An object may have potential energy because of its speed. acceleration. location. momentum. none of the above

location

When a cannon fires a cannonball at a given speed, the smaller recoil speed of the cannon is due to differences in times. masses. forces. momenta.

masses

No work is done by gravity on a bowling ball that rolls along a bowling alley because no force acts on the ball. no distance is covered by the ball. no potential energy converts to kinetic energy. the force on the ball is at right angles to its motion. its kinetic energy may vary.

the force on the ball is at right angles to its motion.

A baseball and a golf ball have the same momentum. Which has the greater kinetic energy? the golf ball the baseball ball Both balls have the same kinetic energy.

the golf ball

Compared to the speed a satellite loses when traveling from nearest to farthest points from Earth, the speed gained when returning from farthest to nearest is less. more. the same.

the same

Planets would crash into the Sun if it weren't for the fact that they are beyond the main gravitation of the Sun. the inverse-square law. their vast distances from the Sun. their tangential velocities. their relatively small masses.

their tangential velocities.

The conservation of momentum is most closely related to Newton's first law. second law. third law.

third law

To catch a fast-moving softball with your bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. Doing this reduces the catching force because the time of catch is increased. relative velocity is more. time of the catch is decreased. relative velocity is less. none of the above

time of catch is increased.

The distinction between impulse and force involves the mass and its effect on resisting a change in momentum. time the force acts. distance the force acts. difference between acceleration and velocity.

time the force acts.

Strictly speaking, if any electrical device in an automobile is turned on (such as an air conditioner, headlights, or radio), more fuel is consumed by the engine. This statement is true only if the engine is running. sometimes true, sometimes false always false true.

true.

A clerk can lift containers a vertical distance of 1 m, or roll them up a 2-m-long ramp to the same elevation. With the ramp, the applied force needed is twice as much. half as much. the same.

twice as much