physics unit 3 vocab

Question 1

work

Answer 1

The transfer of energy by mechanical means; is done when a constant force is exerted on an object in the direction of motion, times the object’s displacement. Is a scalar quantity (F x D = Work), measured in Joules (J = N x m)

Question 2

energy

Answer 2

The ability of an object to produce a change in itself or the world around it.

Question 3

kinetic energy

Answer 3

The energy of an object, resulting from its motion.

Question 4

work-energy theorem

Answer 4

States that when work is done on an object, a change in kinetic energy occurs (W = ∆KE).

Question 5

joule

Answer 5

SI unit of energy, J; 1 J of work is done when a force of 1 N acts on an object over a displacement of 1 m (J = N x m).

Question 6

power

Answer 6

The work done, divided by the time needed to do the work.

Question 7

watt

Answer 7

SI unit of power, W; 1 J of energy transferred in 1 s. (W = J x s)

Question 8

machine

Answer 8

A tool that makes work easier (but does not change the amount of work) by changing the magnitude or the direction of the force exerted to do work.

Question 9

effort force

Answer 9

The force a person exerts on a machine.

Question 10

resistance force

Answer 10

The force exerted by a machine.

Question 11

mechanical advantage

Answer 11

The ratio of resistance force to effort force.

Question 12

ideal mechanical advantage

Answer 12

For an ideal machine, is equal to the displacement of the effort force, divided by displacement of the load.

Question 13

efficiency

Answer 13

The ratio of output work to input work.

Question 14

compound machine

Answer 14

A machine consisting of two or more simple machines that are connected so that the resistance force of one machine becomes the effort force of the second machine.

Question 15

rotational kinetic energy

Answer 15

The kinetic energy of an object, proportional to the object’s moment of inertia and the square of its angular velocity.

Question 16

gravitational potential energy

Answer 16

The stored energy in a system resulting from the gravitational force between Earth and the object.

Question 17

reference level

Answer 17

The position where gravitational potential energy is defined as zero.

Question 18

elastic potential energy

Answer 18

The potential energy that may be stored in an object, such as a rubber band, as a result of its change in shape.

Question 19

Law of Conservation of Energy

Answer 19

States that in a closed, isolated system, energy is not created or destroyed, but rather, is conserved.

Question 20

mechanical energy

Answer 20

The sum of kinetic and gravitational potential energy in a system.

Question 21

elastic collision

Answer 21

A type of collision in which the kinetic energy before and after the collision remains the same.

Question 22

inelastic collision

Answer 22

A type of collision in which the kinetic energy after the collision is less than the kinetic energy before the collision.

Question 23

conduction

Answer 23

The process by which kinetic energy is transferred when particles collide.

Question 24

thermal equilibrium

Answer 24

The state in which the rate of energy flow between two objects is equal and the objects are at the same temperature

Question 25

heat

Answer 25

Energy transferred between two objects in contact with one another and always flows from the hotter object to the cooler object.

Question 26

convection

Answer 26

A type of thermal energy transfer that occurs from the motion of fluid in liquid or gas that is caused by differences in temperature.

Question 27

raditaion

Answer 27

The thermal transfer of energy by electromagnetic waves through the vacuum of space.

Question 28

specific heat

Answer 28

The amount of energy that must be added to a material to raise the temperature of a unit of mass by one temperature unit; is measured in J/(kg * K) [joule per kilogram per kelvin].

Question 29

heat of fusion

Answer 29

The amount of heat required to change 1 kg of a substance from a solid state to a liquid state at its melting point.

Question 30

heat of vaporization

Answer 30

The amount of heat required to change 1 kg of a substance from a liquid state to a gaseous state at its boiling point.

Question 31

first law of thermodynamics

Answer 31

States that the change in thermal energy of an object is equal to the heat that is added to the object, minus the work done by the object.

Question 32

heat engine

Answer 32

A device that continuously converts thermal energy to mechanical energy; requires a high-temperature thermal energy source, a low-temperature receptacle (a sink), and a way to convert the thermal energy into work.

Question 33

entropy

Answer 33

A measure of the disorder in a system.

Question 34

the second law of thermodynamics

Answer 34

States that natural processes go in a direction that maintains or increases the total entropy of the universe.