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Which of the following is not a unit of power?

joule-second

An object as rest may have

potential energy

A moving object does not necessarily have

kinetic energy

An object that has linear momentum must also have

kinetic energy

The total amount of energy in the universe

cannot change

When the speed of a body is doubled

its momentum is doubled

Two balls, one mass 5 kg and the other mass 10 kg, are dropped simultaneously from a window. When they are 1 m above the ground, the balls have the same

acceleration

A bomb dropped from an airplane explodes in midair

its total kinetic energy increases

The operation of a rocket is based upon

conservation of linear momentum

When a spinning skater pulls in her arms to turn faster

her angular momentum remains the same

The work done in holding a 50 kg object at a height of 2 m above the floor for 10 s is

0

The work done in lifting 30 kg of bricks to a height of 20 m is

5880 J

A total of 4900 J is used to lift a 50 kg mass. The mass is raised to a height of

10 m

The work a 300 W electric grinder can do in 5.0 min is

90 kJ

A 150 kg yak has an average power output of 120 W. The yak can climb a mountain 1.2 km high in

4.1 h

A 40 kg boy runs up a flight of staris 4 m high in 4 s. His power output is

392 W

Car A has a mass of 1000 kg and is moving at 60 km/h. Car B has a mass of 2000 kg and is moving at 30 km/h. The kinetic energy of car A is

twice that of car B

A 1 kg object has a potenital energy of 1 J relative to the ground when it is at a height of

0.102 m

A 1 kg object has a KE of 1 J when its speed is

1.4 m/s

The 2 kg blade of an ax is moving at 60 m/s when it strikes a log. If the blade penetrates 2 cm into the log as its KE is turned into work, the average force it exerts is

180 N

A 1 kg ball is thrown in the air. When it is 10 m above the ground, its speed is 3 m/s. At this time m0st of the ball's total energy is in the form of

rest energy

A 10,000 frieght car moving at 2 m/s collides with stationary 15,00 kg freight car. The two cars couple together and move off at

0.8 m/s

A 30 kg girl and a 25 kg boy are standing on frictionless roller skates. The girl pushes the boy, who moves off at 1.0 m/s. The girls speed is

1 kg

work

(W) a process that transfers energy to an object when an object is moved against an opposing force or from rest.

power

the rate of doing work. P=W/t

kinetic energy

energy due to motion

potential energy

"stored" energy

types of energy

-Chemical- fuels
-Mechanical- potential and kinetic (push, pull, drop)
-Electrical- energy of moving charges Ex: used to turn motors
-Radiant- energy that travels through space Ex: from the sun
-Nuclear- changes in the nucleus of an atom

law of conservation of energy

energy can be neither created or destroyed (energy is conserved)

law of conservation of momentum

in the absence of outside forces, the total momentum of a set of objects remains the same no matter how the objects interact with one another.

linear momentum

the measure of the tendency to keep moving at the same speed in the same direction.

collisions

billyards ball?

rockets

the rush of the gases out of the rockets is balanced by the rocket moving upward and thus the total momentum of the entire system=zero!

angular momentum

the measure of the tendency to keep spinning at the same speed in the same direction

law of angular momentum

an object that is spinning tends to keep spinning

spin stabilization

a spinning body tends to maintain the direction of its spin axis as well as the amount of angular momentum

temperature

a relative measure of the amount of heat in a substance. Also, the property that gives rise to sensations of hot and cold.

heat

(unit=Joule) the sum of all kinetic energies of all the separate particles that make up an object (also called initial energy)

specific heat capacity

(unit= kj/kg*C) the amount of heat that must be added to or removed from an object to change its temperature by 1 degree C. Q=mc(change in temp).

metabolism

the biochemical processes by which the energy content of food an animal eats is liberated

density

D=m/V

pressure

1 pa=kg/m*s

buoyancy

(Fb) the difference between the force pulling down on the object (gravity) and the force pushing up on the object (fluid pressure)

archimedes principle

buoyant force on an object in a fluid = weight of fluid displaced by the object.
- This principle holds if the object sinks or floats.
- If the object's weight is greater than the buoyant force, it sinks vice versa

boyle's law

at a constant T and n, the V of any gas is inversely proportional to the applied (external) P on the gas.

charles law

at a constant P and n, the v of any gas is directly proportional to the T of the gas.

ideal gas law

is a mathematical expression relating Boyle's, Charles's and Gay-Lussac's laws at constant number of moles. P1V1/T1=p2V2/T2

kinetic theory of matter

the energy of molecular motion; it is the energy that tends to disorganize matter.

boiling point

the temp at which liquid rapidly begins to turn to gas

melting point

the temp at which a solid turns to a liquid (also called fusion)

heat engines

a device that turns heat into mechanical energy. Ex: gasoline engine or steam turbine at a power plant

thermodynamics

the study of heat transformation

first law of thermodynamics

energy cannot be created nor destroyed only converted from one form to another.

second law of thermodynamics

it is impossible to take heat from a source and change all of it to mechanical energy or work; some heat must be wasted.

entropy

the measure of the disorder of molecules in a substance

charge

1.6022*10^-19 C

coulomb's law

F=KQ1Q2/R2

electric current

the flow of charge from one place to another

circuits

if we connect a wire between the + and - terminals of a battery we get an electrical circuit. The flow of electrons can be measured as a rate which is called an ampere.

electrical potenial energy

charge * potential energy difference. Measured in Volts (V).

ohm's law

I=V/R, where I= current, V= voltage, R= resistance

serial circuits

joined end to end, current flows through all

parallel circuits

joined through different connections, current split between each

power

how much mechanical work you can get out of this particular system. P=IV

conductor

a substance through which electric charge can flow readily. Ex: Metals

insulator

a substance through which electric charge has a difficult time (no to little conductivity). Ex: glass, rubber, plastic, sand, dirt, wood.

semiconductor

in between a conductor and an insulator in its ability to conduct electricity. Semiconductors are used to make transistors, which are devices that can be used as a tiny switch in electrons. Ex: Silicon, germanium

superconductor

a substance that allows electricity to flow through it with zero resistance.

magnetism

a magnet is an object that has a north and south pole and it attracted to other magnets.

force fields

the altered space around a mass (gravity force), and electric charge (electrostatic force), or a magnet force (magnetic force).

oersted's experiment

he noticed that a compass lines up perpendicular to a wire with current running through it. All moving electric charges give rise to magnetic fields!

right hand rule

if we point our thumb on our right hand in the direction of the current flow, our fingers point in the direction of the magnetic field.

electromagnets

a coil of electric wires with a core of iron.

generator

a device that creates electricity from mechanical energy

alternating current

switches direction

direct current

only goes in one direction and comes from a constant source like a battery

Two thermometers, one calibrated in degrees F and the other in degrees C, are used to measure the same temperature. The numerical reading on the fahrenheit thermometer

may be any of these, depending on the temperature

One gram of steam at 100 degrees C causes a more serious burn than 1 g of water at 100 degress C because steam

contains more energy

heat transfer in a gas can occur by

radiation, convection, and conduction

heat transfer in a vacuum can occur by

radiation only

The fluid at the bottom of a container is

under more pressure than the fluid at the top

The pressure of the earths atmosphere at sea level is due to

the gravitational attraction of the earth for the atmosphere

A cake of soap placed in a bathtub of water sinks. The buoyant force on the soap is

less than its weight

The density of freshwater is 1.00 g/cm3 and that of seawater is 1.03 g/cm3. A ship will float

lower in freshwater than in seawater

An icecube whose center consists of liquid water is floating in a glass of water. When the ice melts, the level of water in the glass

remains the same

A person stands on a very sensitive scale and inhales deeply. The reading on the scale

any of the above, depending on how the expanision of the persons chest compares with the volume of air inhaled

At constant pressure the volume of a gas sample is directly proportional to

its absolute temperature

which of the following statement is not correct

all molecules have the same size and mass

molecular motion is not responsible for

buoyancy

absolute zero may be regarded as that temperature at which

molecular motion in a gas would be minimum possible

on a molecular level heat is

kinetic energy

at a given temperature

the molecules in a gas all have the same average energy

the temperature of a gas sample in a container of fixed voume is raised. The gas exerts a higher pressure on walls of its container because its molecules

have higher average velocities and strike the walls more often

The volume of a gas sample is increased while its temperature is held constant. The gas exerts a lower pressure on the walls of its container because its molecules strike the walls

less often

When evaporation occurs, the liquid that remains is cooler because

the slowest molecules remain behind

When vapor condenses into a liquid

it gives off heat

Food cooks more rapidly in a pressure cooker than in an ordinary pot with a loose lid because

the high pressure raises the boiling poinht of water

A heat engine takes in heat at one temperature and turns

some of it into work and ejects the rest at a lower temperature

In any process the maximum amount of heat that can be converted to mechanical energy

depends on the intake and exhaust temperatures

In any process the maximum amount of mechanical energy that can be conveted to heat

is 100%

A frictionless heat engine can be 100% efficient only if its exhaust temperature is

0 K

The physics of a refridgerator most closely resembles the physics of

a heat engine

The working substance used in most refridgerators in a

gas that is easy to liquify

Heat is absorbed by the refrigeratn in a refridgerator when it

vaporizes

The heat a refridgerator absorbs from its contents is

less than it gives off

The seconmd law of thermodynamics does not lead to the conclusion that

the total amopunt of energy in the universe including rest energy is constant

The greater the entropy of a system of particles

the less the order of the system

ethyl alcohol boils at 172 degrees F. The celsius equivalent of this temperature is

78 degrees C

A temperature of 20 degrees C is the same as

68 degrees F

The heat needed to warm 8 kg of water from 20 degress to 70 degrees C is

1680 kJ

When 1 kg of steam at 20 degrees C loses 3 MJ of heat, the result is

water and ice

A 40 concrete block has the dimensions 1m 0.6 m 0.3 m. Its density is

2222 kg/m3

An object suspended from a spring scale is lowered into a pail filledd to the brim with water; and 4 N of water overflows. The scale shows that the object weighs 6 N in the water. The weight in air of the object is

10 N

Lead melts at 330 degrees C. On the absolute scale this temperature corresponds to

603 K

At which of the following temperatures would the molecules of a gas have twice the average kinetic energy they have at room temperature, 20 degrees C

313 degrees C

A heat engine absorbs heat at a temperature of 127 degrees C and exhausts heat at a temperature of 77 degrees C. Its maximum efficiency is

13%

Electric charge

occurs only in seperate parcles of +/- 1.6 * 10^-19 C

A negative electric charge

interacts with both positive and negative charges

A positively charged rod is brought near an isolated metal ball. Which of the sketches best illustrates the arrangement of charges on the ball?

d

Which of the following statements is notr true?

protons and electrons have equal masses

Coulumb's Law for the force between electric charges belongs in the same category as

Newtons law of gravitation

The electric force between a proton and an electron

is stronger than the gravitiational force between them

The electrons in an atom

are some distance away from the nucleus

Atoms and molecules are normally

electrically neutral

An object has a postive electric charge whenever

moving electrons constitute an electric current

superconductivity occurs in certain substance

only at very low temperautres

resistance

ohm

current

ampere

potential difference

volt

power

watt

electric power is equal to

current * voltage

the electric energy lost when a current passes

becomes heat

when a magnetized bar of iron is strongly heated, its magnetization

becomes weaker

All magnetic fields originate in

moving electric charges

The force on an electron that moves in a curvd path must be

one or more of these

a drawing of the field lines of magnitude field provides information on

both the direcion and the strength of the field

magnetic field lines provide convenient way to visualize a magnetic field. Which of the following statements is not true?

the path followed by an electric charge released near a magent corresponds to a field line

A moving electric charge produces

both an electric and magnetic field

the magnetic field of a bar magnet resembles most closely the magnetic field of

a wore loop carrying a direct current

the magnetic field shown in fig 6-51 is produced by

two south poles

the magnetic field lines around a long straight current are

concentric circles around the current

A magent does not exert a force on

a stationary electric charge

a current carrying wire is in a magnetic field with the direction of the current the same as that of the field

the wire has no tendency to move or to turn

An electromagnet

uses an electric current to produce a magnetic field

The nature of the force that is responsible for the operation of an electric motor is

magnetic

A generator is said to "generate electricity." What it actually does is act as a source of

electric energy

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