Element. Physics Ch 6 & 7

According to Kepler, the line from the Sun to any planet sweeps out equal areas of space a. in equal time intervals. b. In half a complete revolution. c. only when the paths are ellipses.

a. in equal time intervals.

Two identical gliders slide toward each other on an air track. One moves at 1 m/s and the other at 2 m/s. They collide, stick, and moves at a. 3/4 m/s. b. 1/6 m/s. c. 1.5 m/s. d. 1/2 m/s. e. 1/3 m/s.

d. 1/2 m/s.

A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of a) 1 kg m/s. b)0 kg m/s. c)more than 5 kg m/s. d)5 kg m/s. e)2 kg m/s.

1 kg m/s.

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the impulse is a)both the same b)greater with the haystack. c)greater with the brick wall.

Both the same

Calculate the kinetic energy of an 84-kg scooter moving at 12 m/s .

KE = 6000 J 1/2mv^2

When you are struck by a moving object, is it favorable that the object makes contact with you over a short time or over a long time? a) Long contact time decreases the magnitude of the average force and is favorable. b) Long contact time increases the magnitude of the average force and is favorable. c) Short contact time increases the magnitude of the average force and is favorable. d)Short contact time decreases the magnitude of the average force and is favorable.

a) Long contact time decreases the magnitude of the average force and is favorable.

The bob of a simple pendulum has its maximum kinetic energy at the a)bottom of its swing. b)top of its swing. c)at all points along its path of swing. d)midpoint between top and bottom.

a)bottom of its swing.

When air drag affects the motion of projectiles, they don't travel a. as far. b. as high. c. both of these d. neither of these

a. as far.

A cannon recoils while firing a cannonball. The speed of the cannon's recoil is relatively small because the a. cannon has much more mass than the cannonball. b. force against the cannon is smaller than against the ball. c. momentum is mainly concentrated in the cannonball. d. momentum of the cannon is smaller.

a. cannon has much more mass than the cannonball.

An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will a. move in the opposite direction at a lower speed. b. move in the opposite direction at 20 m/s. c. move in the opposite direction at a higher speed. d. none of the above

a. move in the opposite direction at a lower speed.

Relative to an initial height, an object raised twice as high has a gravitational potential energy a. twice as much. b. four times as much. c. half as much d. need more information

a. twice as much.

When two vehicles collide, momentum is conserved _______. a)only if deformation of either vehicle does not occur. b) whether the collision is elastic or inelastic. c) if the collision is elastic d) if the collision is inelastic.

b) whether the collision is elastic or inelastic.

Suppose our experimenter repeats his experiment on a planet more massive than Earth, where the acceleration due to gravity is . When he releases the ball from chin height without giving it a push, how will the ball's behavior differ from its behavior on Earth? Ignore friction and air resistance. (Select all that apply.) a)It will stop well short of his face. b)It will take less time to return to the point from which it was released. c)It will take more time to return to the point from which it was released. d)It will smash his face. e)Its mass will be greater.

b)It will take less time to return to the point from which it was released.

Two cars are raised to the same elevation on service-station lifts. If one car is twice as massive as the other, compare their gains of potential energy. a)The less massive car has equal and opposite potential energy compared to the more massive car. b)The car with twice the mass has twice the potential energy. c)The car with twice the mass has half the potential energy. d) Both cars have the same potential energy.

b)The car with twice the mass has twice the potential energy.

If the equally massive cars of the preceding question stick together after colliding inelastically, how does their speed after the collision compare with the initial speed of car A? a)Their speed is zero. b)Their speed is half the initial speed of car A. c)Their speed is twice the initial speed of car A. d)Their speed is equal to the initial speed of car A.

b)Their speed is half the initial speed of car A.

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the stopping force is a)both the same b)greater with the brick wall. c)greater with the haystack.

b)greater with the brick wall.

Two identical arrows, one with twice the kinetic energy of the other, are fired into a bale of hay. Compared with penetration of the slow arrow, the faster arrow penetrates a)four times as far. b)twice as far. c)the same distance. d)more than four times as far. e)none of the abovea

b)twice as far.

Inside a freely-falling elevator, you would have no a. Gravitational force acting on you. b. Normal force acting on you. c. Neither gravitational nor normal force acting on you. d. Both gravitational and normal force acting on you.

b. Normal force acting on you.

A dropped ball gains speed because a. its nature is to become closer to Earth. b. a gravitational force acts on it. c. of inertia. d. its velocity changes.

b. a gravitational force acts on it.

An Earth satellite in an elliptical orbit has its greatest speed a. when farthest from Earth. b. closest to Earth. c. when getting farther from Earth. d. need more information

b. closest to Earth.

According to Kepler, the paths of planets about the Sun are a. circles. b. ellipses. c. straight lines. d. parabolas. e. none of the above

b. ellipses.

Dr. Chuck projects a ball horizontally from a lab bench. The ball lands on a bullseye marked on the floor a horizontal distance equal to the ball's initial speed a. squared plus its downward speed squared when hitting the floor. b. multiplied by its time in the air. c. coupled with its speed of fall. d. all of the above e. none of the above

b. multiplied by its time in the air.

The work you do when pushing a shopping cart twice as far while applying twice the force is a. half as much. b. twice as much. c. four times as much. d. the same amount.

b. twice as much.

Which undergoes the greatest change in momentum (if all of the baseballs have the same speed just before being caught and just after being thrown)? a) A baseball that bounces out of the glove straight down b) A baseball that bounces out of the glove straight up c) A baseball that is caught and then thrown back d) A baseball that is caught

c) A baseball that is caught and then thrown back

When a cannonball is fired, the momentum of the system (cannon + cannonball) is conserved if a) the momentum of the cannon ball is zero. b) the momentum of the cannon is equal to the magnitude of the momentum of the cannon ball and points in the same direction. c) the momentum of the cannon is equal to the magnitude of the momentum of the cannon ball and points in the opposite direction. d) the momentum of the cannon is zero

c) the momentum of the cannon is equal to the magnitude of the momentum of the cannon ball and points in the opposite direction.

Which requires more work: lifting a 50-kg sack a vertical distance of 2 m or lifting a 25-kg sack a vertical distance of 4 m? a)The sack lifted 4 m requires more work. b)The 25 kg sack requires more work. c)Both take the same 1000 J. d)The 50 kg sack requires more work.

c)Both take the same 1000 J.

What does it mean to say that momentum is conserved? a)It means momentum is zero. b)It means the change in momentum is equal to the impulse. c)It means momentum does not change. d)It means the net momentum is zero.

c)It means momentum does not change.

Railroad car A rolls at a certain speed and makes a perfectly elastic collision with car B of the same mass. After the collision, car A is observed to be at rest. How does the speed of car B compare with the initial speed of car A? a)The speed of car B is zero. b)The speed of car B is half the initial speed of car A. c)The speed of car B is equal to the initial speed of A. d)The speed of car B is twice the initial speed of car A.

c)The speed of car B is equal to the initial speed of A.

A bicycle that travels twice as fast as another when braking to a stop will skid a)twice as far. b)sixteen times as far. c)four times as far. d)eight times as far e) depends on the bike's mass

c)four times as far.

After rolling halfway down an incline, a marble's kinetic energy is a)greater than its potential energy. b)less than its potential energy. c)the same as its potential energy.

c)the same as its potential energy.

You're driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum during the time of contact? a. the bug b. your car c. both the same

c. both the same

Compared with falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because the a. stopping time is shorter on the carpet. b. stopping time is longer on the carpet. c. carpet provides a smaller impulse and a longer time. d. carpeted floor provides a smaller impulse.

c. carpet provides a smaller impulse and a longer time.

Which has the greater momentum when moving? a. a container ship b. a bullet c. either of these depending on speed

c. either of these depending on speed

Distinguish between force and impulse. a) Force and impulse are the same. b)Impulse is force per time interval. c)Force is impulse times a time interval. d) Impulse is force times a time interval.

d) Impulse is force times a time interval.

A car is raised a certain distance in a service-station lift, thus giving it potential energy relative to the floor. If it were raised twice as high, how much more potential energy would it have? a)It would have equal and opposite b)potential energy. c)It would have the exact same potential energy. d)It would have twice as much potential energy. e)It would have half as much potential energy.

d)It would have twice as much potential energy.

A circus diver drops from a high pole into water far below. When he is halfway down a)his potential energy is halved. b)he has gained an amount of kinetic energy equal to half his initial potential energy. c)his kinetic energy and potential energy are equal. d)all of the above e)none of the above

d)all of the above

When traveling twice as fast your kinetic energy is increased _______. a)by three. b)by two. c)not at all. d)by four.

d)by four.

Energy cannot be _______. a)transferred. b)transferred, transformed, or destroyed. c)transformed. d)destroyed.

d)destroyed.

To impart the greatest momentum to an object, you must a)exert the greatest force over the shortest time. b)exert the greatest force. c)exert a force over the greatest time. d)exert the greatest force over the longest time.

d)exert the greatest force over the longest time.

If a monkey floating in outer space throws his hat away, the hat and the monkey will both a)move away from each other at the same speed. b)come to a stop after a few minutes. c)move a short distance and then slow down. d)move away from each other, but at different speeds. e)move a short distance and then go faster

d)move away from each other, but at different speeds.

What impulse occurs when the force of 7.0 N acts on the cart for the time 4.0 s ?

p = 28 kg⋅ms Impulse = Ft

When a big fish swims into an oncoming smaller fish and swallows it, the momentum of the two-fish system _______. a)decreases. b)converts to spurious motion. c)remains the same. d)increases.

remains the same.