Chem Test #3

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joule-second

potential energy

kinetic energy

kinetic energy

cannot change

When the speed of a body is doubled

its momentum is doubled

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

0

5880 J

10 m

90 kJ

4.1 h

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

0.102 m

1.4 m/s

180 N

rest energy

0.8 m/s

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

"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.

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

D=m/V

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

1.6022*10^-19 C

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

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

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

buoyancy

absolute zero may be regarded as that temperature at which

molecular motion in a gas would be minimum possible

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

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

is 100%

0 K

a heat engine

The working substance used in most refridgerators in a

gas that is easy to liquify

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

78 degrees C

68 degrees F

1680 kJ

water and ice

2222 kg/m3

10 N

603 K

313 degrees C

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

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

ohm

ampere

volt

watt

electric power is equal to

current * voltage

becomes heat

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

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

magnetic

electric energy

Example: