physics quiz #2

During each second of free fall, the speed of an object a. increases by the same amount. b. changes by increasing amounts each second. c. remains constant. d. doubles each second.

a. increases by the same amount.

Mass is most closely related to a. inertia. b. weight. c. volume. d. location.

a. inertia

When you do 1000 J of work on a car jack and the gravitational potential energy of the car is increased by 300 J, the efficiency of the jack is a. 30%. b. 50%. c. 70%. d. 130%.

a. 30%.

A lead-filled tennis ball and a regular tennis ball are dropped from the top of a tall building at the same time. Air drag does affect motion. Which reaches the ground first? a. The lead-filled one. b. The regular one. c. They both reach the ground at the same time. d. No way to say.

a. The lead-filled one.

A pair of spiral galaxies collide and merge to form one larger elliptical galaxy. Astronomers assume that the momentum of the new elliptical galaxy is a. equal to the sum of the momenta of two spiral galaxies. b. equal to the difference in momenta of the two spiral galaxies. c. the same as the momentum of the more massive spiral galaxy. d. zero.

a. equal to the sum of the momenta of two spiral galaxies.

A lead-filled tennis ball and a regular tennis ball are dropped from the top of a tall building. Air drag does affect motion. The ball that experiences the greater amount of air drag is the a. lead-filled one. b. regular one. c. Neither, for both experience the same amount of air resistance. d. No way to say.

a. lead-filled one.

When Nellie Newton hangs by a pair of ropes at different angles to the vertical, the rope tension is greater in the rope that makes the a. smallest angle to the vertical. b. largest angle to the vertical. c. Depends on the lengths of the ropes. d. All of these, to some degree.

a. smallest angle to the vertical.

A big fish swims up on and swallows a small fish at rest. Right after lunch, the momentum of the big fish is a. the same as before. b. less than before. c. more than before. d. zero.

a. the same as before.

A lunar vehicle is tested on Earth at a speed of 10 km/h. When it travels at the same speed on the Moon, its momentum is a. the same. b. less. c. more. d. zero.

a. the same.

A massive truck and a golf cart have a head-on collision with equal amounts of force. The least amount of acceleration occurs for a. the truck. b. the cart, if it is initially at rest. c. the cart, whether at rest or moving. d. neither, for they undergo the same acceleration.

a. the truck.

An object with a mass of 1 kilogram on Earth a. weighs less on the Moon. b. weighs the same on the Moon. c. weighs more on the Moon. d. weighs the same everywhere.

a. weighs less on the moon

Use Newton's second law to answer this question: The acceleration of a vertically thrown ball at the top of its path is a. 0. b. 10 m/s2. c. between 0 and 10 m/s2. d. dependent on the initial speed of the ball.

b. 10 m/s2.

How much power is required to raise a 200-kg crate a vertical distance of 2 m in a time of 4 s? a. 400 W b. 1000 W c. 1600 W d. 4000 W

b. 1000 W

An axe is swung against a tree with a blow of 4000 N. The force that acts on the axe during this event is a. less than 4000 N. b. 4000 N. c. greater than 4000 N. d. 0.

b. 4000 N.

You run horizontally at 4 m/s in a vertically falling rain that falls at 4 m/s. Relative to you, the raindrops are falling at an angle of a. 0. b. 45. c. 53. d. 90.

b. 45.

A shiny sports car at the top of a vertical cliff has a potential energy of 100 MJ relative to the ground below. Unfortunately, a mishap occurs and it falls over the edge. When it is halfway to the ground, its kinetic energy is a. 25 MJ. b. 50 MJ. c. about 100 MJ. d. more than 100 MJ.

b. 50 MJ.

Which of the following equations most directly illustrates the safety value of automobile airbags? a. F = ma. b. Ft = ∆(mv). c. d = 1/2 at2. d. v = gt.

b. Ft = ∆(mv).

A motorcycle undergoes acceleration when a. ΣF = 0. b. a nonzero net force acts on it. c. it is in equilibrium. d. All of these.

b. a nonzero net force acts on it.

When your mass increases, your weight a. may remain the same. b. also increases. c. decreases. d. transforms to greater volume.

b. also increases

A shoe on an inclined surface barely remains at rest when friction equals the a. weight mg of the shoe. b. component of mg parallel to the surface. c. component of mg perpendicular to the surface. d. None of the above.

b. component of mg parallel to the surface.

As mass is added to a pushed object, its acceleration a. increases. b. decreases. c. remains constant. d. quickly reaches zero.

b. decreases.

When the neck of an air-filled balloon is untied and air escapes, the balloon shoots through the air. The force that propels the balloon is provided by the a. surrounding air. b. ejected air. c. air still in the balloon. d. ground beneath the balloon.

b. ejected air.

Horizontal and vertical components of velocity are equal when the projection angle is a. less than 45. b. equal to 45. c. greater than 45. d. vertical.

b. equal to 45.

Two identical carts have a compressed spring between them. When the spring is released, the carts recoil from each other with oppositely directed accelerations that are a. almost equal. b. equal. c. unequal. d. zero.

b. equal.

If action is a foot kicking a soccer ball, the reaction is an equal force on the a. ball. b. foot. c. ground. d. air drag of motion.

b. foot.

The normal force that acts on a block of ice that slides on a ramp a. is equal to mg at all angles. b. gets progressively less as the slope of the ramp increases. c. becomes greatest when the ramp is vertical. d. None of the above.

b. gets progressively less as the slope of the ramp increases.

For a given force, acceleration and mass are a. directly proportional to each other. b. inversely proportional to each other. c. not related. d. two words for the same concept.

b. inversely proportional to each other.

The net force on a kicked soccer ball can be zero when a. action and reaction both act on the ball. b. it is kicked by two feet with equal and opposite amounts of force. c. it is kicked in the same direction by two feet. d. it is kicked by two feet at right angles to each other.

b. it is kicked by two feet with equal and opposite amounts of force.

When we say that 1 kilogram weighs 10 N, we mean that a. 1 kg is 10 N. b. it's true at Earth's surface. c. it's true everywhere. d. mass and weight are one and the same.

b. it's true at Earth's surface.

A big fish coasts up to and swallows a small fish at rest. Right after lunch, the speed of the big fish is a. the same as before. b. less than before. c. more than before. d. zero.

b. less than before.

The amount of force with which a boxer's punch lands depends on the a. physical condition of the boxer. b. mass of what's being hit. c. boxer's attitude. d. None of these.

b. mass of what's being hit.

If a charging elephant has kinetic energy, it must also have a. potential energy. b. momentum. c. work. d. All of these.

b. momentum.

A dog and a mouse run down the road with the same KE. The faster moving one is the a. dog. b. mouse. c. Both run at the same speed. d. Can't say.

b. mouse.

A piece of clay moving with one unit of momentum strikes and sticks to a heavy bowling ball initially at rest. After the clay sticks, both the clay and ball ideally move with a combined momentum of a. a little less than one unit. b. one unit. c. more than one unit. d. much less than one unit.

b. one unit.

A cart is pushed and undergoes a certain acceleration. If the force is held constant and the mass of the cart doubles, its acceleration would be a. one-quarter. b. one-half. c. the same. d. nearly but not quite twice.

b. one-half.

Standing still on a skateboard, you catch a ball tossed horizontally to you. The mass of the ball is one-tenth your mass. Compared with the speed of the caught ball, the speed that both you and the caught ball acquire is a. the same. b. one-tenth as much. c. 10 times as much. d. 100 times as much.

b. one-tenth as much.

A boulder falls due to gravity. The reaction to the force on the boulder is a. air resistance. b. the boulder pulling up on Earth. c. the boulder being pulled downward by Earth. d. Actually, all of these.

b. the boulder pulling up on Earth.

A ball is tossed into a bale of hay and comes to a stop. If instead, it comes to a stop when hitting a sticky solid wall, the impulse needed to stop it is a. less. b. the same. c. more. d. zero.

b. the same.

Compared with the momentum of a 200-lb man running 10 mi/h, the momentum of a 2000-lb car moving 1 mph is a. zero. b. the same. c. greater. d. less.

b. the same.

Earth pulls on the Moon with a certain force. Relative to this force, the pull of the Moon on Earth is a. a little less. b. the same. c. a little greater. d. much less.

b. the same.

A force is a push or pull that is required to change the a. composition of an object. b. the state of motion of an object. c. color of an object. d. temperature of an object.

b. the state of motion of an object.

A 1-kg ball has twice the speed as a 2-kg ball. Compared with the 1-kg ball, the 2-kg ball has a. the same kinetic energy. b. twice the kinetic energy. c. 4 times the kinetic energy. d. more than 4 times the kinetic energy.

b. twice the kinetic energy.

A force interaction requires at least a. one force. b. two forces. c. an action force. d. a reaction force.

b. two forces.

The force of friction between two surfaces can act a. only when the surfaces move relative to each other. b. whether or not the surfaces move relative to each other. c. even when the surfaces are far apart and not touching. d. only over microscopic distances.

b. whether or not the surfaces move relative to each other.

A 1-kg ball has the same speed as a 10-kg ball. Compared with the 1-kg ball, the 10-kg ball has a. less momentum. b. the same momentum. c. 10 times as much momentum. d. 100 times as much momentum.

c. 10 times as much momentum.

The force of gravity acting on a 2-kg melon is a. 2 kg. b. 10 N. c. 20 N. d. more than 20 N.

c. 20 N.

In an ideal pulley system, a woman lifts an 80-N crate by pulling a rope downward with a force of 20 N. For every 1-meter length of rope shepulls downward, the crate rises a. 50 cm. b. 45 cm. c. 25 cm. d. less than 25 cm.

c. 25 cm.

When two identical cars, one traveling twice as fast as the other, brake to a stop using old-fashioned brakes, the faster car will skid a. the same distance. b. twice as far. c. 4 times as far. d. more than 4 times as far.

c. 4 times as far.

A model airplane moves twice as fast as another identical model airplane. Compared with the kinetic energy of the slower airplane, the kinetic energy of the faster airplane is a. the same for level flight. b. twice as much. c. 4 times as much. d. more than 4 times as much.

c. 4 times as much.

An empty truck traveling at 10 km/h has kinetic energy. How much kinetic energy does it have when its speed is doubled? a. The same KE b. Twice the KE c. 4 times the KE d. More than 4 times the KE

c. 4 times the KE

When a falling object bounces as it hits the ground a. the impulse on it is greater than for stopping it. b. its change in momentum is greater than for stopping. c. Both of these. d. None of these.

c. Both of these.

If a car comes to a full stop when hitting a haystack and when hitting a stone wall, the change in momentum is greater for hitting the a. haystack. b. stone wall. c. Same momentum change in both cases. d. None of the above.

c. Same momentum change in both cases.

The amount of air resistance that acts on a wingsuit flyer (and a flying squirrel) depends on the flyer's a. area. b. speed. c. area and speed. d. acceleration.

c. area and speed.

In the absence of external forces, momentum is conserved in a. an elastic collision. b. an inelastic collision. c. either an elastic or an inelastic collision. d. neither an elastic nor an inelastic collision.

c. either an elastic or an inelastic collision.

A simple machine CANNOT multiply a. force. b. distance. c. energy. d. None of these.

c. energy.

When a squid pushes against water, the squid moves forward because the water a. offers no resistance. b. exerts a net backward force. c. exerts a net forward force. d. has the same density as the fish.

c. exerts a net forward force.

Which of these forms of energy is NOT renewable? a. wind power b. solar power c. fossil-fuel power d. photovoltaic power

c. fossil-fuel power

When an increase in speed doubles the momentum of a moving body, its kinetic energy a. increases, but less than doubles. b. doubles. c. more than doubles. d. depends on factors not stated.

c. more than doubles.

Nets used to catch falling boulders on the side of rocky hillside roadways are more effective than rigid fences because their breakage is reduced by a. less impulse of falling rocks. b. less momentum of falling rocks. c. more time to change the momentum of falling rocks. d. less time to change the momentum of falling rocks.

c. more time to change the momentum of falling rocks.

When you jump vertically upward, strictly speaking, you cause Earth to a. also move upward with you. b. remain stationary. c. move downward. d. move sideways a bit.

c. move downward.

A pendulum bob swings to and fro. Its kinetic energy and its potential energy relative to the bottom of its swing are the same at a. the bottom. b. one-quarter the vertical distance between the bottom and top of the swing. c. one-half the vertical distance between the bottom and the top of the swing. d. the top of the swing.

c. one-half the vertical distance between the bottom and the top of the swing.

When both the force and time of contact are doubled, the impulse on an object is a. unchanged. b. doubled. c. quadrupled. d. decreased.

c. quadrupled.

The force that propels a heavy truck along a highway is provided by a. gravity. b. Newton's laws of motion. c. the highway pushing back on the wheels of the truck. d. the air drag acting on the truck.

c. the highway pushing back on the wheels of the truck.

A cart is pushed and undergoes a certain acceleration. If it were pushed with twice the force while its mass doubles, its acceleration would be a. one-quarter. b. one-half. c. the same. d. nearly but not quite double.

c. the same

When work is done twice as quickly, then the power expended is a. half. b. the same. c. twice. d. 4 times as much.

c. twice.

When you say momentum is conserved, you mean that a. when an impulse acts on an object, its momentum will change. b. momentum can be stored. c. when external impulses don't occur, a system's momentum remains the same before and after an interaction. d. when two objects collide, the mass and velocity of each object will not change.

c. when external impulses don't occur, a system's momentum remains the same before and after an interaction.

When a farmer throws a 3-kg pumpkin at a speed of 4 m/s onto a compost pile, the pumpkin's momentum just before hitting the pile is a. 0 kg•m/s. b. 5 kg•m/s. c. 7 kg•m/s. d. 12 kg•m/s.

d. 12 kg•m/s.

How much work is done on a 200-kg crate that is hoisted 2 m in a time of 4 s? a. 400 J b. 1000 J c. 1600 J d. 4000 J

d. 4000 J

The resultant of a 30-N force and a 40-N force cannot possibly be a. 10 N. b. 50 N. c. 70 N. d. 80 N.

d. 80 N.

The force of air friction (air drag) against a falling sack of potatoes a. acts upward. b. increases with increased area. c. increases with increased speed. d. All of the above.

d. All of the above.

Whenever one object exerts a force on a second object, the second object exerts a force on the first that a. is opposite in direction. b. is equal in magnitude. c. occurs at the same time. d. All of these.

d. All of these.

Which of the following equations is most directly useful for solving a problem that asks for the distance a speeding vehicle skids in coming to a stop? a. F = ma b. Ft = ∆(mv) c. KE = 1/2 mv2 d. Fd = ∆(1/2 mv2)

d. Fd = ∆(1/2 mv2)

Your friend says that impulse equals momentum. Your friend's statement is not correct, and the missing word is a. work. b. acceleration. c. speed or velocity. d. change.

d. change.

When a car is braked to a stop, unless it is a hybrid, its kinetic energy is transformed to a. stopping energy. b. potential energy. c. energy of motion. d. heat.

d. heat.

When a net force acts on an object, its acceleration depends on the object's a. initial speed. b. volume. c. weight. d. mass.

d. mass

A model airplane moves 3 times as fast as another identical model airplane. Compared with the kinetic energy of the slower airplane, the kinetic energy of the faster airplane is a. the same for level flight. b. twice as much. c. 4 times as much. d. more than 4 times as much.

d. more than 4 times as much.

The reason a 10-kg rock falls no faster than a 5-kg rock in free fall is that a. the 10-kg rock has greater acceleration. b. the 5-kg rock has greater acceleration. c. the force of gravity is the same for both. d. the force/mass ratio is the same for both.

d. the force/mass ratio is the same for both.

A mosquito has a collision with the windshield of a massive high-speed truck. The force of impact on the mosquito is ________ the force on the truck, and the acceleration of the mosquito is ________ the deceleration of the truck. a. less than; less than b. more than; less than c. the same as; less than d. the same as; more than

d. the same as; more than

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

d. uranium.

When you jump from an elevated position to the ground below, the force you experience when landing does NOT depend on a. the jumping height. b. the softness or hardness of the ground. c. how much you bend your knees. d. your attitude about jumping.

d. your attitude about jumping.

When Jake tosses a ball while standing still on his skateboard, he and his skateboard recoil. If he goes through the motions of tossing the ball, but doesn't toss it, his net recoil will ideally be a. the same as if he threw the ball. b. almost as much as if he threw the ball. c. very small. d. zero.

d. zero.