PHY EXAM 2 QUIZZES

Two cylinders, with the same size and mass, roll down an incline. The cylinders begin at the same height on the incline. Cylinder A has most of its mass concentrated at the rim, while cylinder B has most of its mass concentrated at the center. Which reaches the bottom of the incline first?

B

Two identical masses are attached to two identical springs so that each mass oscillates simple harmonically. Mass A is pulled a distance x from equilibrium; mass B is pulled a distance 4x. Which of the following correctly links the energies of the two masses? -EA = EB, since the masses and springs are identical. -EA = (1/4)EB, since B is pulled 4 times farther. -EA = 4EB, since B is pulled 4 times farther. -EA = 16 EB, since B is pulled 4 times farther. -EA = (1/16)EB, since B is pulled 4 times farther.

-EA = (1/16)EB, since B is pulled 4 times farther.

You have 4 identical 10 kg masses. Two of the masses are connected by a very light bar with length 1 m, and the other two are connected by another very light bar with length 1.5 m. Call the short barbell A and the long barbell B. Which of the following statements is correct? -It will be easier to start A rotating than B. -It will be equally easy to start either barbell rotating. -It will be easier to start B rotating than A.

-It will be easier to start A rotating than B.

A skier moves down a mountain side at constant speed. Which of the following is true? -Only the force pointed uphill do work. -There is no work done by any force. -Several forces do work, but the net work is zero. -Only the forces pointed downhill do work.

-Several forces do work, but the net work is zero.

You are using a wrench to loosen a rusty bolt. Which of the arrangements shown is most effective in loosening the bolt? IMAGE

2

If the intensity of a sound is one million times larger than the threshold of hearing, then the sound intensity level in decibels is

60 dB

A spring-loaded toy dart gun is used to shoot a dart straight up in the air, and the dart reaches a maximum height of 24 m. The same dart is shot straight up a second time from the same gun, but this time the spring is compressed only half as much before firing. How far up does the dart go this time? Ignore any frictional effects.

6m

For two travelling waves to form standing waves, the waves must have the same wavelengths. amplitudes. speeds. or all?

ALL

Wave motion in a material medium involves the propagation of a disturbance. interparticle interactions. the transfer of energy. all of the preceding.

ALL

Jack and Jill are both moving with the same velocity (same speed in the same direction). A stationary sound source is between them so that Jack is moving away from the source and Jill is moving towards it. Which of the following is correct? Compared to the emitted frequency, Jack hears a lower frequency and Jill hears a higher frequency. Compared to the emitted frequency, Jack and Jill both hear a lower frequency. Compared to the emitted frequency, Jack and Jill both hear a higher frequency. Compared to the emitted frequency, Jack hears a higher frequency and Jill hears a lower frequency. They hear the same frequency because they have the same speed.

Compared to the emitted frequency, Jack hears a lower frequency and Jill hears a higher frequency.

PICTURE The figures above represent sound waves emitted by a moving source. Which picture represents a source moving at supersonic speed?

D

PICTURE #26 A mass is attached to a spring and oscillates on a frictionless table. If the mass is at its equilibrium position at t=0, which of the following plots correctly shows the potential energy of the mass as a function of time?

D

PICTURE #26 A mass is attached to a spring and oscillates on a frictionless table. If the mass is at its most positive possible position at t=0, which of the following plots correctly shows the kinetic energy of the mass as a function of time?

D

Two students are entering a building. One takes a single flight of stairs from the sidewalk to the entrance. The other student follows a ramp that has two sections leading from the sidewalk to the entrance. The student who followed the ramp has done more work against gravity because his path was longer. True or False

False

When using an intravenous injection (IV) system to deliver medication to patients, the patient's blood pressure is unimportant. true or false

False

Light waves are special kinds of transverse waves that always have the same speed (in vacuum). Given this, how does the wavelength of higher-frequency blue light compare to the wavelength of lower frequency red light?

The wavelength of red light is LONGER than the wavelength of blue light.

A rigid body is spinning with a constant angular speed. As you observe it, this speed decreases, but the body remains unchanged. What can you infer? about the internal/external force having a torque?

There must be some external force exerting a torque.

If the net work done by an object is negative, the object's kinetic energy decreases. T OR F

True

There are two identical springs, A and B, that have the same spring constant k. Spring A is stretched twice as far as spring B. The magnitude of the force due to spring A is two times larger than that due to spring B. T OR F

True

Two piano wires are hung from a ceiling in a lab. Each wire is connected to a 10-kg mass. The wires are both cylindrical and made from steel. If wire A has twice the diameter of wire B, which of the following correctly describes the relationships between the strains? -Wire B has 2 times the strain of wire A. -Wire B has 4 times the strain of wire A. -Wire A has 4 times the strain of wire B. -Wire A has 2 times the strain of wire B.

Wire B has 4 times the strain of wire A.

You are driving a car around a circular track. Which of the following statements are true? -Your angular momentum will decrease if you increase your tangential speed. -Your angular momentum will increase if you decrease your tangential speed. -Your angular momentum will increase if you increase your tangential speed. -Your angular momentum will be unchanged if you change your tangential speed.

Your angular momentum will increase if you increase your tangential speed.

Imagine you are at a concert with two speakers on opposite sides of a stage. As you walk to your seat along the center aisle (so that you are equal distances from each speaker at all times), you should expect to hear

a constant sound intensity

Imagine you are at a concert with two speakers on opposite sides of a stage. As you walk to your seat along a side aisle (so that you are different distances from each speaker at all times), you should expect to hear

a sound intensity that varies as you get nearer to the stage.

One radian is

about 57.3-degrees.

The maximum acceleration of an object in simple harmonic motion depends on the phase constant. depends on the length of the spring. depends on the angular frequency. depends on the amplitude. depends on the position of the object at t=0. which correct

all

For translational motion of a rigid body, -the velocities of constituent particles depend on their locations in the body. -all constituent particles of the body share the same velocity as the center-of-mass. -only the center-of-mass has a velocity. -the center-of-mass cannot move.

all constituent particles of the body share the same velocity as the center-of-mass.

A solid disk and a ring roll down an incline. The ring is slower than the disk...

always. The ring is always slower regardless of the relative values of the mass or radius.

Think about an object whose momentum is originally 5 kg m/s in the positive x-direction. Later, the object's momentum is 5 kg m/s in the negative x-direction. Which of the following best describes the object's motion?

at some point the object experiences a force

The total energy of an object can be...

can be either positive or negative, depending on the potential energy's zero point.

the value of The gravitational potential energy of an object can be...

can have any value depending on the choice of reference point.

what value can the gravitational potential energy of an object have?

can have any value depending on the choice of reference point.

Water waves with large amplitudes (like those that form tsunamis) speed with amplitudes ?

can move faster or slower than waves with smaller amplitudes.

When pulleys have significant mass, the tension in the string that passes over them

changes as you move around the pulley.

A cannonball is following the trajectory of a frictionless projectile. When it reaches its maximum height, it explodes. The center-of-mass of the fragments go where

continues along the parabolic path towards the ground.

A blood platelet drifts along with the flow of blood through an artery that is partially blocked by deposits. As the platelet moves from the narrow region to the wider region, its speed

decreases

A change in gravitational potential energy depends on...

depends only on the initial and final heights.

A change in gravitational potential energy depends on...

depends only on the initial and final positions.

A race car travels around a circular track. As it moves, it increases its speed around the track. In this case, the total acceleration experienced by the car is a vector that points directly at the center of the track. true or false

false

An object moves with simple harmonic motion only if the object is a mass attached to a spring. T or F

false

The velocity vector of an object in uniform circular motion ALWAYS points towards the center of the circular path. true or false

false

When you use a wrench to loosen or tighten a bolt, the entire force that you apply to the wrench causes a torque. true or false

false

The work done by a variable force can be calculated by simply taking the maximum force times the displacement. T OR F

false - w=Fd

PICTURE The figure above shows the wavefronts generated by an airplane flying past an observer A at a speed greater than that of sound. After the airplane has passed, the observer reports hearing

first nothing, then a sonic boom, then the sound of engines.

As a motorcycle drives down a road, one of its tires ruptures. This sends pieces of rubber flying through the air. The pieces of rubber go through the air how?

follow straight-line paths along the direction of their velocity vector at the time of the rupture.

Imagine you are standing along a street waiting for a friend to pick you up. A car passes you while the driver blasts his horn. The frequency of the sound you hear is

higher than the emitted frequency as the car approaches and lower than the emitted frequency as the car moves away.

Beats are a direct result of

interference

The total mechanical energy of a system is conserved when...

is conserved when there are no nonconservative forces present.

The total mechanical energy of an object in simple harmonic motion

is constant

The conservation of momentum is guaranteed when...

is guaranteed if the net force on a system is zero.

A force acts on an object causing a torque (so the object will move along a circular path). The only component of the force that does work

is the component that is tangential to the circular path.

Compared to the amount of work required to stretch a spring by 1 cm, the amount of work required to compress a spring by 1 cm

is the same amount and has the same sign.

PICTURe #28 A string is clamped at both ends and plucked so it vibrates in a standing mode between the two extreme positions a and b shown in the figure. Let upward motion correspond to positive velocities. When the string is in position b, the instantaneous velocity of points along the string

is zero everywhere

A bomb slides along a horizontal, frictionless surface at a constant speed in the positive x-direction. It explodes into three fragments. Two fragments have equal magnitude but oppositely directed momenta. What can you say about the third fragment and its direction?

it must move in the postitive x-direction

The best model of solar system formation is that a giant spherical gas cloud shrinks (its radius gets smaller), forming a central star. The cloud does not have any nearby neighbors that can exert forces on it. If the gas cloud is slowly rotating in its initial, large radius state,

it must rotate faster after it shrinks.

In an experiment, you measure the time it takes an object in simple harmonic motion to return to its initial location. You have measured

its period

An ice cube floats in a glass of water in a way that part of the ice cube is above the water level. You put your finger on the cube, submerge it completely, and hold it there. The buoyant force is

largest when you have submerged the ice cube because more water is displaced.

Which of the following objects has the smallest kinetic energy? An object with mass 2m and speed 3v. mass 3m and speed 2v. mass m and speed 4v. mass 4m and speed v.

mass 4m and speed v.

Observers A & B hear sounds from a source that is at rest. Observer A is moving towards the source, and observer B is at rest with respect to the source. Observer A regarding wavelength and speed

measures the same wavelength as observer B but a larger wave speed.

In a simple pendulum, the magnitude of the force that causes simple harmonic motion is

mg sinθ.

The kinetic energy of an object that rolls without slipping must have both...

must have contributions from its translational and rotational motions.

Object A has twice the mass of object B. Object A is attached to a cable that hangs from the ceiling in a room. If object B is attached to an identical cable in the same room, then

object A will have the same period of oscillation as object B.

Object A has triple the mass of object B. Object A is attached to a cable that hangs from the ceiling in a room. If object B is attached to an identical cable in the same room, then how will object a oscillate ?

object A will oscillate with the same frequency as object B.

Equal forces are applied to objects A and B, but object A is more massive than object B. If the forces act on A and B for equal amounts of time, what are the changes in momentum?

objects A and B experience equal changes in momentum.

Your friend is yelling to you across a parking lot. You expect the sound to reach you fastest

on a hot, humid day

PIC The traces above show beats that occur when two different pairs of waves are added. For which of the two is the difference in frequency of the original waves greater?

pair 1

PICTURE The distances between the resident and the alarms must be different by some number of half-wavelengths of the tone.

pair 1

Constructive and destructive interference of sound waves depends on

phase difference.

If the kinetic energy of an object increases from one moment to the next, what kind of work is being done on the object ?

positive work is being done on the object.

The speed of sound is generally greatest in

solids

When two waves meet and interfere, the resulting wave is determined by

superposition

A ball is attached to a rope and swung in a vertical circle. The ball is not in uniform circular motion due to the acceleration due to gravity. true or false

true

A ball is attached to a rope and swung in a vertical circle. The speed of the ball changes most rapidly when the ball is halfway between the top and the bottom. true or false

true

A firecracker sits at rest on the ground. When it explodes, it is ripped into multiple pieces that scatter in all directions. The momentum of the firecracker system after the explosion is zero. true or false

true

A race car travels around a circular track. As it moves, it increases its speed around the track. In this case, the centripetal acceleration experienced by the car is a vector that points directly at the center of the track. true or false

true

If wave A and wave B have the same period, but A's wavelength is twice that of B, then wave A has to move a twice the speed of B. T or F

true

In a car crash, a passenger's impulse is fixed by the fact that they come to a halt after initially having some velocity. An airbag works by decreasing the force applied to the passenger by increasing the time over which the impulse occurs. true or false

true

In uniform circular motion, the velocity vector always lies along a direction tangent to the circular path. true or false

true

The angular distance traveled by an object is equal to is arc length divided by its radial distance. true or false

true

Two masses collide elastically. Both kinetic energy and momentum are conserved. true or false

true

Two solid disks rotate with the same angular speed. Disk A has a radius that is twice as large as Disk B. Compared to a point at the edge of Disk B, a point at the edge of Disk A will have what linear speed?

will have twice the linear speed.

As you enter a store, a turnstile bar must be rotated out of the way. One end of the bar is attached to a rotating hub, while the other is free. To minimize the amount of force that must be applied, -you should push as far from the free end of the bar as possible. -you can push at any location along the bar. -you should push right at the middle of the bar. -you should push as close to the free end of the bar as possible.

you should push as close to the free end of the bar as possible.

A bullet sits in a gun. The mass of the bullet is much smaller than the mass of the gun. Upon firing the bullet, how would you expect the bullet and gun to move

you would expect the bullet and gun to move in opposite directions, with the bullet having the larger speed.

The reference point for gravitational potential energy may be.....

zero, neg, pos

In a laboratory, you are observing two bars of different material. The identical-length bars are placed into a hydraulic press (one at a time) that will apply the same stress to each. Bar A is compressed by 5 mm, while bar B is compressed by 3 mm. Which of the following is true? -Bar B has a larger shear modulus. -Bar B has a larger Young's modulus. -Bar A has a larger shear modulus. -Bar A has a larger Young's modulus.

Bar B has a larger Young's modulus.

An object is moving without accelerating. You expect the momentum

to remain constant

A student can apply a torque of 15 N-m to every door (which acts like a thin rectangular sheet) she encounters. To enter a building, the student must open an outer door with a mass of 25 kg. Once inside, she must open an inner door of identical size, but the mass is only 10 kg. Which of the following is true? -Neither door has an angular acceleration. -The angular acceleration of the inner door is the same as the angular acceleration of the outer door. -The angular acceleration of the inner door is larger than the angular acceleration of the outer door. -The angular acceleration of the inner door is smaller than the angular acceleration of the outer door.

-The angular acceleration of the inner door is larger than the angular acceleration of the outer door.

Imagine you are designing a vertical spinning wheel for a game show. Contestants will grab the wheel at its edge, apply a force tangent to the wheel, and watch it spin. You make two prototype wheels with the same mass and radius, but one is a solid disk while the other is a hoop. For a given contestant's applied force, -they will have equal angular accelerations. -the hoop will have a larger angular acceleration. -the solid disk will have a larger angular acceleration.

-the solid disk will have a larger angular acceleration.

A wheel has a radius of 0.5 m and rotates with an angular speed of 0.5 rad/s. If the wheel rolls without slipping, what is the center-of-mass speed?

.25 m/s

A stress is applied to a long thin bar of metal causing the length to change by 10% of its original length. The strain is

0.1

A 1-kg rock is suspended by a massless string from one end of a 1-m measuring stick. What is the mass of the measuring stick given the picture above? IMAGE

1.0kg

For a standing wave on a rope, the distance between two adjacent antinodes is

1/2 wavelength

A container is filled with oil and fitted on both ends with pistons. The area of the left piston is 10 mm-squared; that of the right piston is 10,000 mm-squared. What force must be exerted on the left piston to keep the 10,000 N car on the right at the same height?

10 N

Imagine you are at the middle of the surface a frozen lake that is frictionless. Which of the following scenarios would get you to the edge in the shortest amount of time? -Pick a direction you'd like to move and then throw your boots as hard as possible in that direction. -Pick a direction you'd like to move and then throw your boots very softly in that direction. -Pick a direction you'd like to move and then throw your boots very softly in the opposite direction. -Pick a direction you'd like to move and then throw your boots as hard as possible in the opposite direction.

Pick a direction you'd like to move and then throw your boots as hard as possible in the opposite direction.

Two students are using the side of a building for stretching before a run. Student A pushes on the wall so that her arms are perpendicular to the wall. Student B pushes on the wall so that her arms make an angle smaller than 90-degrees with the wall. If the students arms are equal strength and their hands have the same area, which of the following is correct? stress on wall?

Student A creates a greater stress on the wall.

A passenger car that has tires with radius = 0.3 m travels along a highway. The car pulls alongside a tractor-trailer that has tires with radius = 0.6 m and moves with the same velocity. If the tires roll without slipping, which of the following statements is correct? -The angular speed of the car's tires is smaller than the angular speed of the tractor's tires. -The angular speed of the car's tires is equal to the angular speed of the tractor's tires. -The angular speed of the car's tires is larger than the angular speed of the tractor's tires.

The angular speed of the car's tires is larger than the angular speed of the tractor's tires.

Imagine you are standing on a skateboard. If you step off the board at its front, which of the following will conserve linear momentum? -The board has to move the opposite way with a smaller speed than you. -The board has to move in the same direction as you with the same speed. -The board has to move the opposite way with a higher speed than you. -The board has to move the opposite way with the same speed as you.

The board has to move the opposite way with a higher speed than you.

On the first Tuesday of every month a town tests its tornado alarm system. Each alarm produces a single-wavelength tone. A resident finds that standing in a particular spot significantly reduces the volume of the alarms. Which of the following must be true for this to occur? -The distances between the resident and the alarms must be different by some number of half-wavelengths of the tone. -The distances between the resident and the alarms must be different by some number of wavelengths of the tone. -The distances between the resident and the alarms must be equal to the wavelength of the tone.

The distances between the resident and the alarms must be different by some number of half-wavelengths of the tone.

Blood flows through a coronary artery that is partially blocked by deposits along the artery wall. Through which part of the artery is the flow rate (volume of blood per unit time) largest?

The flow rate is the same in both parts.

Which of the following scenarios accurately describes the flow of an incompressible fluid through a pipe with a length of 10 feet and diameter of 2 inches to a pipe with a length of 10 feet and diameter of 1 inch?

The flow speed increases as the diameter decreases because the same amount of mass that enters from the large pipe must exit from the smaller pipe.

PICTURE Three observers, A, B, and C, are listening to a moving source of sound. The diagram below shows the location of the wavecrests of the moving source with respect to the three observers. Which of the following is true? The frequency of the sound is highest at A. The frequency of the sound is highest at C. The frequency of the sound is highest at B. The wavecrests move faster at A than at B and C. The wavecrests move faster at C than at A and B.

The frequency of the sound is highest at C.

In a lab, you are experimenting with two springs - spring A is stiff (has a large k), spring B is soft (has a small k). Spring A has a length that is twice that of spring B. If you hang an identical mass on each spring and give them the same initial displacement, which of the following is correct? -The mass on spring A will have a shorter period of oscillation than the mass on spring B, and the amplitude of A's motion will be larger than B's. -The mass on spring A will have a longer period of oscillation than the mass on spring B, and the amplitude of A's motion will be larger than B's. -The mass on spring A will have a longer period of oscillation than the mass on spring B, but the amplitudes of their motions will be equal. -The mass on spring A will have a shorter period of oscillation than the mass on spring B, but the amplitudes of their motions will be equal.

The mass on spring A will have a shorter period of oscillation than the mass on spring B, but the amplitudes of their motions will be equal.

A vertical tube of water has the same radius and height as a vertical tube of mercury. Mercury has a larger density than water. Which tube has the larger pressure at the bottom?

The mercury tube because it has the larger mass.

As you sit on your front porch, a fire truck drives down the street towards your house. The fire truck has a siren that emits a continuous sound. Which of the following situations correctly describes the sound wave that you hear? The observed sound wave has a larger wavelength and higher frequency than the wave emitted by the siren. The observed sound wave has a shorter wavelength and lower frequency than the wave emitted by the siren. The observed sound wave has a larger wavelength and lower frequency than the wave emitted by the siren. The observed sound wave has a shorter wavelength and higher frequency than the wave emitted by the siren.

The observed sound wave has a shorter wavelength and higher frequency than the wave emitted by the siren.

A basketball (a thin spherical shell) and a solid plastic ball have the same mass and radius. If they are both spun about an axis along their diameters with the same angular speed, which has more KE

the basketball has more KE

The potential energy of a spring depends on

the difference between the length of the spring and its equilibrium length.

If a torque does negative work on an object, what will the angular acc. be

the final angular speed of the object is smaller than the initial angular speed of the object.

Two people and a dog are in a park. Jack is 10 m from the dog and Polly is 20 m away from the dog. When the dog barks, -the intensity of the sound at Jack's position is 2-times larger than at Polly's position. -the intensity of the sound at Polly's position is 4-times larger than at Jack's position. -the intensity of the sound at Jack's position is 4-times larger than at Polly's position. -the intensity of the sound at Jack's position is equal to the intensity at Polly's position.

the intensity of the sound at Jack's position is 4-times larger than at Polly's position.

If the speed of an object doubles (increases by a factor of 2) what does KE do?

the kinetic energy increases by a factor of 4.

A child sits at the center of a rotating merry-go-round. If she slides towards the edge, what does the merry go round do?

the merry-go-round should slow down.

Rockets work because momentum wise...

the momentum of the exhaust gas is equal and opposite to the momentum of the rocket.

The momentum of an object depends on

the product of its mass and velocity.

A mass hangs on a vertical spring. Initially, the mass is at its equilibrium point. As the mass is stretched away from equilibrium at constant speed, what kind of work does the spring do on the mass?

the spring does negative work on the mass.

In an isolated system with nonconservative forces how will the total mechanical energy be conserved?

the total mechanical energy will not be conserved but the total energy will be.

In an elastic collision what happens with the KE

the total value of the system's kinetic energy does not change.

Imagine a system with two particles that initally has zero linear momentum. Later, you observe that the particles are moving away from each other. If there is no net force on the system, how will the particles be moving?

then the particles must be moving in exactly opposite directions, but they may have different speeds.