Physics review

The formula changeU =nCvchangeT for the change in the internal energy of a fixed amount of an ideal gas is valid

for any process involving that fixed amount of the gas.

thin uniform bar has a moment of inertia about an axis perpendicular to it through its center. If both the mass and length of this bar are halved, its moment of inertia about the same axis will be

(1/8)I

To triple both the pressure and the volume of a fixed amount of an ideal gas, you would multiply its absolute temperature by

9

String is wrapped around the outer rim of a solid uniform cylinder that is free to rotate about a frictionless axle through its center. When the string is pulled with a force tangent to the rim, it gives the cylinder an angular acceleration . Part A If the cylinder had twice the radius, but everything else was the same, the angular acceleration would be

Alpha/2

Which has a greater buoyant force on it, a 21.0- piece of wood floating with part of its volume above water or a 21.0- piece of submerged iron?

the submerged iron

Two small objects of equal weight are attached to the ends of a thin weightless bar that spins about an axis perpendicular to the bar at its center. Each mass is a distance from the axis of rotation. The system spins at a rate so that its kinetic energy is If both masses are now moved closer in so that each is d/7 from the rotation axis, while the angular velocity does not change, the kinetic energy of the system will be

(1/49)K

Two unequal masses and are attached to a thin bar of negligible mass that rotates about an axis perpendicular to the bar. When is a distance from the axis and is a distance from the axis, the moment of inertia of this combination is . If the masses are now interchanged, the moment of inertia will be

(13/4)I

A pendulum on earth swings with angular frequency . On an unknown planet, it swings with angular frequency 2. The acceleration due to gravity on this planet is

(G/4)

If samples of these two gases are at the same temperature, what must be true about the motion of the molecules?

-The average kinetic energy is the same for both gases. -The rms speed of the hydrogen molecules is times greater than that of the nitrogen molecule

A ball of mass 0.400 is whirled in a horizontal circle at the end of a light string 75.0 long at a speed of 3.00 . If the string is lengthened to 2.00 while the ball is being twirled, then the speed of the ball will now be

1.13 m/s

A certain transverse wave is described by the equation Y(x,t)=(10.5mm) sin2pi... Determine this wave's amplitude.

10.5mm

For the process shown in the pv diagram below...

12x10^5 J

An object with mass suspended by a spring vibrates with frequency . When a second object is attached to the first, the system now vibrates with frequency /4.00 The mass of the second object is

15.0 M

A string that is 9.6 long is tied between two posts and plucked. The string produces a wave that has a frequency of 320 and travels with a speed of 192 . How many full wavelengths of the wave fit on the string?

16

horizontal cylindrical pipe has a part with a diameter one quarter that of the rest of the pipe. If is the speed of the fluid in the wider section of pipe, then the speed of the fluid in the narrower section is

16V

Calculate the volume of 1.36 of liquid water at a temperature of 20 (at which its density is 998 )

2.45x10^-5 m^3

A heavy solid disk rotating freely and slowed only by friction applied at its outer edge takes 60 seconds to come to a stop. If the disk had twice the radius and twice the mass, but the frictional force remained the same, the time it would it take the wheel to come to a stop from the same initial rotational speed is

240 s

An organ pipe open at one end, but closed at the other, is vibrating in its fundamental mode, producing sound of frequency 1200 . If you now open the closed end, the new fundamental frequency will be

2400 Hz

A segment of wire stretched tightly between two posts a distance apart vibrates in its fundamental mode with frequency .A segment of an identical wire is stretched with the same tension, but between two different posts. You observe that the frequency of the sacond harmonic of wire is the same as the fundamental frequency of wire . The length of wire must be

2L

If this object is replaced by one of mass 4 , the new object vibrates with a period

2T

A cylindrical metal bar conducts heat at a rate from a hot reservoir to a cold reservoir. If both its length and diameter are tripled, it will conduct heat at a rate

3R

A sphere radiates energy at a rate of 1.70 when its temperature is 100 . At what rate will it radiate energy if its temperature is increased to 200 ? (Neglect any heat transferred back into the sphere.)

4.40 J/s

A thin metal rod expands 1.6 when its temperature is increased by 2.0 . If an identical rod of the same material, except triply as long, also has its temperature increased by 2.0 , it will expand

4.8 mm

If the power plant uses a Carnot cycle and the desired theoretical efficiency is 6.5 , from what depth must cold water be brought?

400m

A violinist is tuning her instrument to concert A (440 ). She plays the note while listening to an electronically generated tone of exactly that frequency and hears a beat of frequency 4 , which increases to 5 when she tightens her violin string slightly. What was the frequency of her violin when she heard the 4- beat?

444 Hz

Calculate the volume occupied by 1.36 of steam at 200 . Assume the steam is at atmospheric pressure and can be treated as an ideal gas.

5.28×10^−2 m^3

The thermal conductivity of concrete is 0.80 , and the thermal conductivity of a certain wood is 0.10 . How thick would a solid concrete wall have to be to have the same rate of heat flow as an 6.4- -thick solid wall of this wood? Both walls have the same surface area and the same interior and exterior temperatures.

51 cm

When a wheel turns through one complete rotation, the angle (in radians) that it has turned through is closest to

6

A cube that is 9.0 on a side is made from a material with a density of 800 . The cube floats in a fluid that has a density of 1200 . How much of the height of the cube is underneath the surface of the water?

6.0 cm

Part E What will be the speed of these waves (in terms of ) if we increase by a factor of 18.0, which stretches the wire to double its original length?

6.00 V

If all of this gas is put into a box having sides of length 0.5 without changing its temperature, the pressure it exerts on the walls of the larger box will be

8p

If it takes time T to make its first revolution, in time 3T the disk will make

9 revolutions

If the gauge pressure at a depth in a lake is , the gauge pressure at a depth will be

9P

If you mix different amounts of two ideal gases that are originally at different temperatures, what must be true of the final state after the temperature stabilizes? (There may be more than one correct choice.) A. Both gases will reach the same final temperature. B. The final rms molecular speed will be the same for both gases. C. The final average kinetic energy will be the same for both gases.

A,C

The graph in the figure shows the temperature as a function of time for a sample of material being heated at a constant rate. What segment or segments of this graph show the sample existing in two phases (or states)?

AB

Assume you have moles of an ideal gas initially at a volume . Along which process will the most work be done by the gas on its surroundings as it expands to a volume of 3 V?

An isobaric expansion

Which of the following must be true about an ideal gas that undergoes an isothermal expansion? (There may be more thanone correct choice.) A. No heat enters the gas. B. The pressure of the gas decreases. C. The internal energy of the gas does not change. D. The gas does positive work.

B,C,D

If this engine is used as a heat engine, what is the direction of the cycle, clockwise or counterclockwise?

Clockwise

You perform 100 of work on a refrigerator that extracts heat from a cold reservoir and dumps heat into a hot reservoir. The amount of heat dumped into the hot reservoir must

Greater than 100 J

GYMNAST QUESTION While the turntable is being accelerated, the person suddenly extends her legs. What happens to the turntable?

Its acceleration decreases

Suppose you put a hot object in contact with a cold object and observe (with some wonder) that heat flows from the cold object to the hot object, making the cold one colder and the hot one hotter.This process would violate

Only the second law of thermodynamics

person pushes vertically downward with force on a lever of length that is inclined at an angle above the horizontal as shown in the figure below . The torque that the person's push produces about point A is

PLcos(theta)

To get her violin perfectly tuned to concert A, should she tighten or loosen her string from what it was when she heard the 4- Hz beat?

She should loosen her string

If both the mass of the bob and the length of the pendulum are tripled, the new period will be

Sqrrt 3T

When a mass hangs from a vertical wire of length , waves travel on this wire with a speed . What will be the speed of these waves if we triple without stretching the wire?

Sqrrt 3V

What will be the speed of these waves if we stretch the wire to thrice its original length?

Sqrrt3V

In a study of the biomechanics of the tug-of-war, a 2.0- -tall, 80.0- competitor in the middle of the line is considered to be a Rigid body leaning back at an angle of 30.0 to the vertical...if the competitor leans slightly farther back. It remains stationary in this new position, which statement is true

The difference between T1 and T2 increases, balancing the increased torque about his feet that his weight produces when he leans farther back

Compare the entropy change of the warmer water to that of the colder water during one cycle of the heat engine, assuming an ideal Carnot cycle

The entropy of the warmer water decreases by the same amount that the entropy of the colder water increases

GYMNAST QUESTION If the body's center of mass were not placed on the rotational axis of the turntable, how would the person's measured moment of inertia compare to the moment of inertia for rotation about the center of mass?

The measured moment of inertia would be too large

Which of the following statements is correct concerning the temperature changes of both substances? (Ignore the signs of the temperature changes in your answer.)

The temperature change of the copper is greater than the temperature change of the water

A person listening to a siren from a stationary police car observes the frequency and wavelength of that sound. The car nowdrives rapidly toward the person

The wavelength of the sound the person observes will be shorter than it was, and the frequency will also be higher than it was

In terms of the thermodynamic cycle of this refrigerator, this electrical energy is equal to

The work done on the gas

The steam occupies a volume _______ orders of magnitude greater than that occupied by the liquid water.

Three

What will be the speed of these waves if we replace the wire with an identical one, except twice as long?

V

If the linear speed of point b is V, then the linear speed of point a is

V/9

What will be the speed of these waves if we replace the wire with one of the same length, but two times as heavy?

V/sqrrt2

When two wires of identical dimensions are used to hang 25.0- weights, wire is observed to stretch three times as much as wire B From this observation, what conclusion can you make about the Young's moduli of these wires?

YA= 1/3 YB