# First & Second Law Of Thermodynamics – Physics

### Practice Test 3-5 Of First & Second Law Of Thermodynamics – Physics

This chapter is about first & second law of thermodynamics, specific heat and latent heat – Physics.

A hydraulic jack has a mechanical advantage allowing a puny human to lift a car. Which of the following statements is true?

The work done by the input piston is equal to the work done by the output piston.

A hydraulic lift is designed with an output cylinder that has 36 times the area of the input cylinder. If a force F is applied to the input cylinder, the output cylinder can supply a force equal to

36 F

A hydraulic lift is designed with an input cylinder that has 1/5 the diameter of the output cylinder. If a force F is applied to the input cylinder, the output cylinder can supply a force equal to

25 F

Boyle’s Law can be stated mathematically as PV=constant. This translates to:

P and V are inversely proportional

Diving in your swimming pool, you let out a stream of bubbles. As they rise towards the surface they

increase in diameter.

According to Archimedes’ Principle, the bouyant force

is equal to the weight of the displaced fluid

A block of wood is floating in water with 2/3 of its volume below the water line. The density of the wood is

equal to 2/3 the density of water

Water flows through pipe A into pipe B. Pipe B is larger and has three times the cross-sectional area that pipe A has. Compared to the speed of the water in pipe A, the speed in pipe B is:

1/3

Water flows through a 2cm diameter pipe connected to a 1cm diameter pipe. Compared to the speed of the water in the 2cm pipe, the speed in the 1cm pipe is:

A large gravel truck is loosely covered with a tarpaulin. The edges of the tarp are tied down to the truck. When the truck is at rest the tarp is flat. When it cruises at highway speeds

the tarp bows up

Absolute zero temperature

-is the temperature where all molecular motion ceases.

– can never be reached by cooling any object.

– is -273.2 degrees Celsius.

When two objects at different temperatures are placed in thermal contact, heat flows

from the higher temperature object to the lower temperature object.

The amount of heat necessary to change the temperature of 1 gram of substance by 1 degree Celsius is called the substance’s

specific heat

Latent heat is always

involved in a phase change

An amount of heat is added to ice, raising its temperature from -10 degrees Celsius to -5 degrees Celsius. A larger amount of heat is added to the same mass of liquid water, raising its temperature from 15 degrees Celsius to 20 degrees Celsius. From these results, we conclude that

the specific heat of ice is less than the specific heat of liquid water

When water boils in Denver, Colorado (elevation 5200 ft) its temperature is

less than the temperature of boiling water in Dallas, Texas (elevation 450 ft)

When the temperature of a quantity of gas is increased

the pressure and/or the volume must increase

The heat transfer process in which heat flows directly through the material is

conduction

The specific heat of liquid water is

one calorie per gram degree Celsius

When water is at its melting temperature

80 calories must be removed for each gram that is to be frozen

A heat engine

always rejects some heat to a lower temperature reservoir

The efficiency of a heat engine is given by the ratio of

net work done/amount of heat supplied

no heat flows into or out of the system

It’s hot as blue blazes outside so you stand in front of your refrigerator with the door open to cool off. If you stand there long enough

the room will eventually get warmer

The average kinetic energy of the particles in a system is called

temperature

A heat engine takes in 500 J of energy from the hot reservoir in one cycle while performing 200 J of work. The amount of heat transferred to the cold reservoir in the same time is

300 J

Entropy is

a quantity that increases as the disorder of a system increases

An inventor has created a heat engine that extracts energy from geothermal hot spots and geysers like Old Faithful at Yellowstone National Park. She claims to turn all of the geothermal energy into work. Such a device is

a violation of Kelvin’s statement of the second law of thermodynamics

The efficiency of a Carnot engine would be increased if

he high and low temperatures were both lowered by 100 degrees Celsius

An amount of water forms a single hexagonally symmetric snowflake. Elsewhere the same amount of water is a droplet of liquid water. Which state has higher entropy?

The droplet of liquid water, since it is more unruly and can adopt almost any shape

what is the formula for pressure?

P= Force/Area

what is the basis of Pascal’s Principle?

Any change in the pressure of a fluid is transmitted uniformly in all directions throughout the fluid

define atmospheric pressure

the pressure of the layer of air that surrounds the earth

* decreases with altitude

who invented the barometer?

Torricelli

the viscosity of fluid is

a measure of the frictional effects within the fluid

the larger the viscosity …

the larger the frictional forces between different layers of the fluid

what is the zeroth law of thermodynamics

Two or more objects in thermal equilibrium have the same temperature

(thermal equilibrium is when the physical properties are no longer changing)

latent heat is

The amount of heat needed per unit mass to produce a phase change

In an isobaric process

the pressure of the gas remains constant

In an isothermal process

the temperature does not change

In conduction

heat flows through a material when objects at different temperatures are placed in contact with one another

In convection

heat is transferred by the motion of a fluid containing thermal energy

heat energy is transferred by electromagnetic waves

Efficiency is

the ratio of the net work done by the engine to the amount of heat that must be supplied to accomplish this work

Carnot efficiency

is the maximum efficiency possible for any engine taking in heat from a reservoir at absolute temperature TH and releasing heat to a reservoir at temperature TC

The first law of thermodynamics

requires that, for a complete cycle, the heat released at the higher temperature must equal the energy put into the engine in the form of both heat and work

the second law of thermodynamics

Heat will not flow from a colder body to a hotter body unless some other process is also involved

When a glass rod rubbed with silk acquires a positive charge, the silk acquires…

a negative charge

A rod with a positive charge is brought near a positively charged pith ball. The pith ball is suspended from an insulating string. The pith ball will be…

repelled by the rod

If the distance between two point charges is doubled while the size of the charges remains the same, the force between the charges is multiplied by…

0.25

If the distance between two point charges remains constant while the size of one of the charges is doubled, the force between the charges is multiplied by…

2

Materials that allow electric charges to move freely are called…

conductors

The unit for electrical charge is…

Coulomb

Electric field lines are envisioned as…

radiating inward toward a negative charge and out of a positive charge

The normal tendency of positive charges is to…

move to regions of lower electric potential

The change in electric potential is equal to…

the change in electrostatic energy divided by the amount of the charge.

The unit for electric potential is…

volt

Electric current is…

the charge per unit time

The unit for electrical current is…

amperes

Electrical resistance is…

the property of a circuit element that opposes the flow of current

The unit of electrical resistance is…

ohms

Resistances connected in a series all have…

the same current

Resistances connected in parallel all have…

the same potential difference

Power supplied by a battery is calculated as…

the potential difference times the current

The power dissipated by a resistance may be calculated as…

the square of the current times the resistance.

A voltmeter is always connected…

in parallel with the circuit element whose potential difference is to be measured.

Household circuits are wired in…

parallel to a direct current source

The magnetic field lines produced by a current in a straight wire…

are directed in concentric circles around the wire.

Electrons flow around a circular wire loop in a horizontal plane, in a direction that is clockwise when viewed from above. This causes the magnetic field. Inside the loop, the direction of this magnetic field is…

down

The north pole of a magnetic compass needle points towards the north geographic pole of the earth because…

there is a south magnetic pole near the north geographic pole.

Which of the following cannot induce a current in a loop of wire? A. a stationary magnet inside the stationary loop. B. moving the loop near a magnet. C. moving a magnet near the loop. D. changing the current in nearby loop.

a stationary magnet inside the stationary loop.

A transformer is used to either increase or decrease the voltage in an AC circuit. When the output voltage is greater than the input voltage of a transformer then…

the power output is the same as the power input

Two long bar magnets are aligned so that north poles face each other. The magnets are separated by 1 cm, and a repulsive force between the north poles is 0.080 N. When the separation is increased to 2 cm the force will be…

0.020 N

Imagine a magnetic field pointing into the plane of this page (screen). An electron moves across the page (screen) from left to right. The direction of the magnetic force on the electron will be…

toward the bottom of the page (screen)

A transformer has 200 turns on the primary coil and 20 turns on the secondary coil. The primary coil is connected to a direct current source of 100 millivolts. The voltage in the secondary coil will be…

zero

High AC voltages are desirable for long distance transmission of electric power because…

the higher the voltage the lower the current, which reduces the power lost.

According to Faraday’s Law of Electromagnetic Induction the induced voltage is equal to…

the rate of change of the magnetic flux

The force between two unlike magnetic poles…

decreases as the square of the separation distance between them.

The magnetic field lines of a bar magnet…

emerge from the north pole and go into the south pole

If the distance between two point charges is tripled while the size of the charges remains the same, the force between the charges is multiplied by…

1/9

If the distance between two point charges remains constant while the size of each of the charges is quadrupled, the force between the charges is multiplied by…

16

Can you charge an object without actually touching it with another charged object..

Yes, this is an example of charging by induction

If the distance between two point charges remains constant while the size of one of the charges is quadrupled, the force between the charges is multiplied by…

4

The SI unit of magnetic field is the…

Telsa

Which of the following cannot induce a voltage in a loop of wire? A. Expanding or contracting the loop in a region where there is no magnetic field. B. moving the loop near a magnet. C. moving a magnet near the loop. D. changing the current in a nearby loop.

expanding or contracting the loop in a region where there is no magnetic field.

A generator has a coil of wire rotating in a magnetic field. If the rotation rate increases, how is the maximum output voltage of the generator affected?

the maximum voltage increases

A 6 V battery is connected to the primary coil of a transformer with 200 turns around the iron core. What is the voltage across the output terminals of the transformer if there are 400 turns on the secondary coil?

The output voltage is zero.

The primary coil of a cell phone charging transformer with 200 turns is plugged into the wall outlet (120 V) in a house in draws 0.1 A of current. What is the output charging current of the secondary coil of the transformer that has 20 turns?

The output current is greater than 0.1 A.

A horizontal wire carries a current straight toward you. From your point of view the magnetic field caused by this current…

circles the wire in a counterclockwise direction.

A current carrying circular loop of wire lies flat on the table top. When viewed from above, the current moves around the loop in a counterclockwise sense. What is the direction of the magnetic field inside the loop caused by this current?

The magnetic field points straight up

A current carrying circular loop of wire lies flat on a table top. When viewed from above, the current moves around the loop in a counterclockwise sense. what is the direction of the magnetic field outside the loop caused by this current?

magnetic field points straight down.

The location of maximum motion of a standing wave is

an antinode

The number of wave pulses per unit time is the

frequency of the wave

Which of the following is an example of longitudinal waves?

sound waves

The distance between the same points on successive pulses is the

wavelength of the wave

The time between successive wave pulses is the

period of the wave

A wave disturbance in which the displacement in the medium is parallel to the direction of wave travel is a

longitudinal wave

If you increase the tension of a string, the velocity of the wave on the string

increases

Water waves pass the end of a pier every four seconds. What is the frequency of the water waves?

0.25 Hz

A rowboat tied to a dock moves up and down with the water waves through a total distance of 40cm. The amplitude of the water waves is

20cm

A tuning fork for the “A” note vibrates with 440Hz. What is the frequency of the note that is one octave above the tuning fork?

880Hz

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