## 104 terms

### impulse

The area under the curve on a Force versus time (F vs. t) graph represents...

work

kinetic energy

momentum

impulse

### zero

When you sit on a chair, the resultant force on you is...

down

depending on your weight

up

zero

### They both are going the same speed.

Consider two masses m1 and m2 at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which m1 sits is at an angle of 30° with the horizontal, while the plane on which m2 sits is at 60°. If the masses are released, which is going faster at the bottom of its plane?

m2

They both are going the same speed.

cannot be determined without knowing the masses

m1

### it is moving in a circle

Consider a particle moving with constant speed such that its acceleration of constant magnitude is always perpendicular to its velocity....

it is moving in a circle

None of these are definitely true all of the time.

it is moving in a parabola

it is moving in a straight line

### is constant, only if conservative forces act.

The total mechanical energy of a system...

is constant, only if conservative forces act.

is either all kinetic energy or all potential energy, at any one instant.

is equally divided between kinetic energy and potential energy.

can never be negative.

### 2a

A net force F accelerates a mass m with an acceleration a. If the same net force is applied to mass m/2, then the acceleration will be...

a/4

a/2

4a

2a

### less than 30 J

A ball drops some distance and loses 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did the ball gain?

more than 30 J

exactly 30 J

cannot be determined from the information given

less than 30 J

### four times as much

You are throwing a ball for the second time. If the ball leaves your hand with twice the velocity it had on your first throw, its horizontal range R (compared to your first serve) would be...

four times as much

twice as much

1.4 times as much

half as much

### quadruples

Two objects attract each other gravitationally. If the distance between their centers is halved, the gravitational force...

doubles

is cut in half

is cut to one fourth

quadruples

### 10m/s

A ball is thrown with a velocity of 20 m/s at an angle of 60° above the horizontal. What is the horizontal component of its instantaneous velocity at the exact top of its trajectory?

17m/s

zero

10m/s

20m/s

### the square of the distance between the two objects.

The gravitational force between two objects is inversely proportional to...

the square of the distance between the two objects.

the square of the product of the masses of the two objects.

the product of the masses of two objects.

the distance between the two objects.

### It is never beyond the pull of Earth's gravity.

A spaceship is traveling to the Moon. At what point is it beyond the pull of Earth's gravity?

when it gets above the atmosphere

when it is half-way there

when it is closer to the Moon than it is to Earth

It is never beyond the pull of Earth's gravity.

### the kinetic energy of the object

The quantity 1/2 mv2 is...

the work done on the object by the force

the potential energy of the object

the kinetic energy of the object

the power supplied to the object

### parabola

A soldier throws a grenade horizontally from the top of a cliff. Which of the following curves best describes the path taken by the grenade?

circle

hyperbola

ellipse

parabola

### Neither; both experienced the same magnitude impulse.

A Ping-Pong ball moving east at a speed of 4 m/s, collides with a stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse during the collision?

the Ping-pong ball

It's impossible to tell since the velocities after the collision are unknown.

the bowling ball

Neither; both experienced the same magnitude impulse.

### Yes, since the choice of the zero of potential energy is arbitrary.

Is it possible for a system to have negative potential energy?

No, because this would have no physical meaning.

Yes, since the choice of the zero of potential energy is arbitrary.

No, because the kinetic energy of a system must equal its potential energy.

Yes, as long as the total energy is positive.

### less than mg

An object of mass m is hanging by a string from the ceiling of an elevator. The elevator is moving upward, but slowing down. What is the tension in the string?

zero

greater than mg

exactly mg

less than mg

### increases until it is equal to the product of µs and the normal force on the rock.

Glaciers push rocks in front of them. Before a stationary rock starts moving as a result of the force Fglacier exerted on it, the static friction between the rock and the ground...

increases until it is equal to the product of µs and the normal force on the rock.

decreases until it is equal to the product of µs and the normal force on the rock.

remains constant until it is smaller than Fglacier.

decreases until it is smaller than Fglacier.

### (GM/r)1/2

Consider a small satellite moving in a circular orbit (radius r) about a spherical planet (mass M). Which expression gives this satellite's orbital velocity?

(GM/r)1/2

(GM/r2)1/2

GM/r

GM/r2

### a frictional force is acting on it.

A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that

a net downward force is acting on it.

it may be accelerating.

a frictional force is acting on it.

it is not acted on by appreciable gravitational force.

### velocity decreased.

You are standing in a moving bus, facing forward, and you suddenly fall forward. You can imply from this that the bus's...

speed remained the same, but it's turning to the right.

speed remained the same, but it's turning left.

velocity increased.

velocity decreased.

### Newton's 3rd law

If you blow up a balloon, and then release it, the balloon will fly away. This is an illustration of...

Newton's 3rd law

Galileo's law of inertia

Newton's 2nd law

Newton's 1st law

### is directed toward the center of the circular path.

When an object experiences uniform circular motion, the direction of the net force is...

in the opposite direction of the motion of the object.

in the same direction as the motion of the object.

is directed away from the center of the circular path.

is directed toward the center of the circular path.

### 9 times yesterday's power output.

Compared to yesterday, you did 3 times the work in one-third the time. To do so, your power output must have been...

one-third of yesterday's power output.

9 times yesterday's power output.

3 times yesterday's power output.

the same as yesterday's power output.

### increase

A package of supplies is dropped from a plane, and one second later a second package is dropped. Neglecting air resistance, the distance between the falling packages will...

decrease

depend on their weight

increase

be constant

### If an object is acted on by a non-zero net external force, its momentum will not remain constant.

Which of the following is an accurate statement?

If the kinetic energy of an object is doubled, its momentum will also double.

The momentum of a moving object is constant.

If an object is acted on by a non-zero net external force, its momentum will not remain constant.

The momentum of a projectile is constant.

### elastic

In a game of pool, the white cue ball hits the #5 ball and stops, while the #5 ball moves away with the same velocity as the cue ball had originally. The type of collision is...

completely inelastic

any of these, depending on the mass of the balls

inelastic

elastic

### trajectory

The path of a projectile through space is called its:

equilibrant

range

trajectory

torque

### The object pulling upward on the Earth with force mg.

An object of mass m sits on a flat table. The Earth pulls on this object with force mg, which we will call the action force. What is the reaction force?

The table pushing up on the object with force mg.

The object pushing down on the table with force mg.

The object pulling upward on the Earth with force mg.

The table pushing down on the floor with force mg.

### equal to g

Suppose a satellite were orbiting the Earth just above the surface. What is its centripetal acceleration?

impossible to say without knowing the mass

larger than g

equal to g

smaller than g

### exactly mg

An object of mass m is hanging by a string from the ceiling of an elevator. The elevator is moving up at constant speed. What is the tension in the string?

greater than mg

less than mg

exactly mg

cannot be determined without knowing the speed

### K is less than U.

A ball falls from the top of a building, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?

It is impossible to tell.

K is less than U.

K is greater than U.

K is equal to U

### Yes, although the speed is constant, the direction of the velocity can be changing.

Is it possible for an object moving with a constant speed to accelerate? Explain.

Yes, if an object is moving it can experience acceleration

Yes, although the speed is constant, the direction of the velocity can be changing.

No, if the speed is constant then the acceleration is equal to zero.

No, an object can accelerate only if there is a net force acting on it.

### more than 30 J

A ball drops some distance and gains 30 J of kinetic energy. Do not ignore air resistance. How much gravitational potential energy did the ball lose?

more than 30 J

exactly 30 J

less than 30 J

cannot be determined from the information given

### T2/R3

Let the average orbital radius of a planet be r. Let the orbital period be T. What quantity is constant for all planets orbiting the Sun?

T/R2

T/R

T2/R3

T3/R2

### 32F

Two objects, with masses m1 and m2, are originally a distance r apart. The gravitational force between them has magnitude F. The second object has its mass changed to 2m2, and the distance is changed to r/4. What is the magnitude of the new gravitational force?

F/16

16F

32F

F/32

### be over the bomb

A pilot drops a bomb from a plane flying horizontally at a constant speed. Neglecting air resistance, when the bomb hits the ground the horizontal location of the plane will...

be in front of the bomb

depend on the speed of the plane when the bomb was released

be behind the bomb

be over the bomb

### much less than v

A very light object moving with speed v collides head-on with a very heavy object at rest, in a frictionless environment. The collision is almost perfectly elastic. The speed of the heavy object after the collision is...

much less than v

equal to v

slightly less than v

slightly greater than v

### in elastic collisions

When is kinetic energy conserved?

in inelastic collisions

in elastic collisions

in all collisions

in any collision in which the objects do not stick together

### the stone

A stone is thrown horizontally from the top of a tower at the same instant a ball is dropped vertically. Which object is traveling faster when it hits the level ground below?

the stone

the ball

It is impossible to tell from the information given.

neither, since both are traveling at the same speed

### zero

A rocket moves through empty space in a straight line with constant speed. It is far from the gravitational effect of any star or planet. Under these conditions, the force that must be applied to the rocket in order to sustain its motion is...

dependent on how fast it is moving

equal to its weight

equal to its mass

zero

### the brick

A brick and a feather fall to the earth at their respective terminal velocities. Which object experiences the greater force of air friction?

It cannot be determined because there is not enough information given.

Neither, both experience the same amount of air friction.

the brick

the feather

### equal in magnitude but point in opposite directions.

Action-reaction forces are...

unequal in magnitude but point in the same direction.

equal in magnitude but point in opposite directions.

unequal in magnitude and point in opposite directions.

equal in magnitude and point in the same direction.

### they hit at the same time

A bullet is fired horizontally, and at the same instant a second bullet is dropped from the same height. Ignore air resistance. Compare the times of fall of the two bullets...

the fired bullet hits first

the dropped bullet hits first

they hit at the same time

cannot tell without knowing the mass of the bullets

### It is never beyond the pull of Earth's gravity.

A spaceship is traveling to the Moon. At what point is it beyond the pull of Earth's gravity?

when it gets above the atmosphere

when it is closer to the Moon than it is to Earth

when it is half-way there

It is never beyond the pull of Earth's gravity.

### increases

If the net work done on an object is positive, then the object's kinetic energy...

increases

decreases

is zero

remains the same

### it is less than its initial speed

When a football in a field goal attempt reaches its maximum height, how does its speed compare to its initial speed?

it is less than its initial speed

it is greater than its initial speed

it is equal to its initial speed

it is zero

### 45°

At what angle should a water-gun be aimed in order for the water to land with the greatest horizontal range?

45°

0°

60°

30°

### the ball

A rubber ball and a lump of putty have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the wall. Which objects experiences the greater momentum change?

the ball

the putty

Cannot be determined from the information given.

Both experience the same momentum change.

### is zero

Ignoring air resistance, the horizontal component of a projectile's acceleration...

remains a non-zero value

continuously decreases

continuously increases

is zero

### The vectors are perpendicular.

An object moves in a circular path at a constant speed. Compare the direction of the object's velocity and acceleration vectors...

Both vectors point in the same direction.

The vectors point in opposite directions.

The vectors are perpendicular.

The question is meaningless, since the acceleration is zero.

### move with constant velocity

In the absence of an external force, a moving object will...

stop immediately

go faster and fater

move with constant velocity

slow down and eventually come to a stop

### Both objects experience the same magnitude of momentum change.

A small object collides with a large object and sticks. Which object experiences the larger magnitude of momentum change?

Both objects experience the same magnitude of momentum change.

cannot be determined from the information given

the large object

the small object

### the power supplied to the object by the force.

The quantity Fd/t is...

the work done on the object by the force.

the kinetic energy of the object.

the power supplied to the object by the force.

the potential energy of the object.

### its mass

The acceleration of an object is inversely proportional to

the net force acting on it

its position

its mass

its velocity

### remains constant

Ignoring air resistance, the horizontal component of a projectile's velocity

remains constant

continuously decreases

continuously increases

is zero

### g/8

A hypothetical planet has a mass of half that of the Earth and a radius of twice that of the Earth. What is the acceleration due to gravity on the planet in terms of g, the acceleration due to gravity at the Earth?

g

g/4

g/8

g/2

### The total momentum both before and after the collision is zero.

A 3.0-kg object moves to the right at 4.0 m/s. It collides head-on with a 6.0-kg object moving to the left at 2.0 m/s. Which statement is correct?

None of these answers is true.

The total momentum before the collision is 24 kg∙m/s, and after the collision is 0 kg∙m/s.

The total momentum both before and after the collision is zero.

The total momentum both before and after the collision is 24 kg∙m/s.

### K increases and U decreases.

An acorn falls from a tree. Compare its kinetic energy K, to its potential energy U.

K increases and U increases.

K decreases and U increases.

K decreases and U decreases.

K increases and U decreases.

### decreases

If the net work done on an object is negative, then the object's kinetic energy...

increases

is zero

remains the same

decreases

### slightly less than 3.0 m/s.

A golf ball traveling 3.0 m/s to the right collides in a head-on collision with a stationary bowling ball in a friction-free environment. If the collision is almost perfectly elastic, the speed of the golf ball immediately after the collision is...

slightly less than 3.0 m/s.

slightly more than 3.0 m/s.

much less than 3.0 m/s.

equal to 3.0 m/s.

### Newton's 3rd law

Two cars collide head-on. At every moment during the collision, the magnitude of the force the first car exerts on the second is exactly equal to the magnitude of the force the second car exerts on the first. This is an example of

Newton's 3rd law

Newton's 2nd law

Newton's 1st law

Newton's law of gravitation

### 4m

Two planets have the same surface gravity, but planet B has twice the radius of planet A. If planet A has mass m, what is the mass of planet B?

4m

1.41m

0.707m

m

### Kepler

Who was the first person to realize that the planets move in elliptical paths around the Sun?

Copernicus

Einstein

Brahe

Kepler

### watt/second

Of the following, which is not a unit of power?

newton-meter/second

joule/second

watt/second

watt

### 0 J

A 50-N object was lifted 2.0 m vertically and is being held there. How much work is being done in holding the box in this position?

100 J

0 J

more than 100 J

less than 100 J but more than 0 J

### constant acceleration

A constant net force acts on an object. Describe the motion of the object....

constant speed

increasing acceleration

constant acceleration

constant velocity

### It remains the same.

A child falls sideways off a sled while sledding on frictionless ice. What happens to the velocity of the sled?

It remains the same.

It increases.

Cannot be determined from the information given.

It decreases.

### it decreases

A freight car moves along a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to the velocity of the car?

it decreases

in increases

it remains the same

cannot be determined from the information given

### the red ball

Two equal mass balls (one red and the other blue) are dropped from the same height, and rebound off the floor. The red ball rebounds to a higher position. Which ball is subjected to the greater magnitude of impulse during its collision with the floor?

the red ball

the blue ball

Both balls were subjected to the same magnitude impulse.

It's impossible to tell since the time intervals and forces are unknown.

### always be F.

IIf you exert a force F on an object, the force which the object exerts on you will...

always be F.

depend on whether or not the object is moving.

depend on whether or not you are moving.

depend on the relative masses of you and the object.

### a/8

A net force F acts on a mass m and produces an acceleration a. What acceleration results if a net force F/2 acts on mass 4m?

2a

a/8

4a

8a

### remains constant at zero

If you push twice as hard against a stationary brick wall, the amount of work you do...

is cut in half

doubles

remains constant but non-zero

remains constant at zero

### is smaller than the force the rock exerts on you.

You are pushing a rock along level ground and making the rock speed up. How does the size of the friction force exerted by the ground on the rock compare with the size of the force the rock exerts on you? The force of friction...

is larger than the force the rock exerts on you.

is the same size as the force the rock exerts on you.

could be any of the above; it depends on other factors.

is smaller than the force the rock exerts on you.

### 30° and 60°

An Olympic athlete throws a javelin at four different angles above the horizontal, each with the same speed: 30°, 40°, 60°, and 80°. Which two throws cause the javelin to land the same distance away?

30° and 80°

30° and 60°

40° and 60°

not possible

### 0J

A 3.0-kg object moves to the right at 4.0 m/s. It collides in a perfectly inelastic collision with a 6.0 kg object moving to the left at 2.0 m/s. What is the total kinetic energy after the collision?

36J

24J

72J

0J

### The speed of B is equal to the speed of A.

Satellite A has twice the mass of satellite B, and rotates in the same orbit. Compare the two satellite's speeds.

The speed of B is twice the speed of A.

The speed of B is equal to the speed of A.

The speed of B is half the speed of A.

The speed of B is one-fourth the speed of A.

### static friction

The force that keeps you from sliding on an icy sidewalk is

weight

static friction

normal force

kinetic friction

### kg m2/s3

What is the correct unit of power expressed in SI units?

kg m/s2

kg m2/s2

kg m2/s3

kg2 m/s2

### The small car and the truck experience the same average force.

A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average collision force is correct?

The small car experiences the greater average force.

It is impossible to tell since the masses and velocities are not given.

The small car and the truck experience the same average force.

The truck experiences the greater average force.

### nearly 3v

A very heavy object moving with velocity v collides head-on with a very light object moving with velocity -v. The collision is elastic, and there is no friction. The heavy object barely slows down. What is the speed of the light object after the collision?

nearly infinite

nearly v

nearly 2v

nearly 3v

### increases as it nears the sun

The speed of Halley's Comet, while traveling in its elliptical orbit around the Sun...

increases as it nears the sun

is zero a two points in the orbit

decreases as it nears the sun

is constant

### the force on the truck is equal to the force on the car.

A 20-ton truck collides with a 1500-lb car and causes a lot of damage to the car. Since a lot of damage is done on the car...

the truck did not slow down during the collision.

the force on the truck is equal to the force on the car.

the force on the truck is smaller than the force on the car.

the force on the truck is greater then the force on the car.

### It increases to more than double its original value.

A horizontal force accelerates a box from rest across a horizontal surface (friction is present) at a constant rate. The experiment is repeated, and all conditions remain the same with the exception that the horizontal force is doubled. What happens to the box's acceleration?

It increases to less than double its original value.

It increases to exactly double its original value.

It increases to more than double its original value.

It increases somewhat.

### more than mg, and pointing up.

A pilot executes a vertical dive then follows a semi-circular arc until it is going straight up. Just as the plane is at its lowest point, the force on him is

more than mg, and pointing down.

less than mg, and pointing up.

more than mg, and pointing up.

less than mg, and pointing down.

### the same

Compared to its mass on the Earth, the mass of an object on the Moon is

less

half as much

the same

more

### There is not a force leading to your fall.

You are standing in a moving bus, facing forward, and you suddenly fall forward as the bus comes to an immediate stop. What force caused you to fall forward?

There is not a force leading to your fall.

gravity

force due to friction between you and the floor of the bus

normal force due to your contact with the floor of the bus

### momentum of the cannonball and cannon is conserved.

When a cannon fires a cannonball, the cannon will recoil backward because the...

energy of the cannonball and cannon is conserved.

momentum of the cannonball and cannon is conserved.

energy of the cannon is greater than the energy of the cannonball.

momentum of the cannon is greater than the energy of the cannonball.

### Kinetic energy is lost.

In an inelastic collision, if the momentum is conserved, then which of the following statements is true about kinetic energy?

Kinetic energy is also conserved.

None of these choices are correct.

Kinetic energy is gained.

Kinetic energy is lost.

### µk < µs.

It's more difficult to start moving a heavy carton from rest than it is to keep pushing it with constant velocity, because...

µs < µk.

the normal force is greater when the carton is at rest.

initially, the normal force is not perpendicular to the applied force.

µk < µs.

### They both slide to the same height.

A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a greater height?

cannot be determined from the information given

They both slide to the same height.

The lightweight object, because it weighs less.

The heavy object, because it has greater kinetic energy.

### g downward

A roller coaster car is on a track that forms a circular loop in the vertical plane. If the car is to just maintain contact with track at the top of the loop, what is the minimum value for its centripetal acceleration at this point?

0.g5 downward

g downward

g upward

2g upward

### four times as much

An object is released from rest a height h above the ground. A second object with four times the mass of the first if released from the same height. The potential energy of the second object compared to the first is...

one-fourth as much

twice as much

one-half as much

four times as much

### first

Which of Newton's laws best explains why motorists should buckle-up?

first

law of gravitation

third

second

### equal to g

Suppose a satellite were orbiting the Earth just above the surface. What is its centripetal acceleration?

smaller than g

equal to g

larger than g

Impossible to say without knowing the mass.

### always act on different objects.

Action-reaction forces....

always act on the same object.

may be at right angles.

sometimes act on the same object.

always act on different objects.

### the product of the masses of two objects.

The gravitational force between two objects is proportional to

the square of the product of the masses of the two objects.

the distance between the two objects.

the product of the masses of two objects.

the square of the distance between the two objects.

### 1.41r

Two planets have the same surface gravity, but planet B has twice the mass of planet A. If planet A has radius r, what is the radius of planet B?

1.41r

0.707r

r

4r

### zero

If you walk 5.0 m horizontally forward at a constant velocity carrying a 10-N object, the amount of work you do is

equal to 50 J

more than 50 J

zero

less than 50 J, but more than 0 J

### move with constant speed

When the rocket engines on the starship NO-PAIN-NO-GAIN are suddenly turned off, while traveling in empty space, the starship will...

slowly slow down, then stop

move with constant speed

stop immediately

go faster and faster

### No, because of the way work is defined.

Can work be done on a system if there is no motion?

Yes, if an outside force is provided.

Yes, since motion is only relative.

No, because of the way work is defined.

No, since a system which is not moving has no energy.