energy, work, power

Question 1

Energy

Answer 1

The ability to do work

Question 2

Kinetic energy

Answer 2

The energy of motion

Question 3

Potential energy

Answer 3

Energy that is stored

Question 4

Mechanical energy

Answer 4

The combination of kinetic and potential energy

Question 5

Work

Answer 5

The transfer of energy

Question 6

Mechanical work

Answer 6

Applying a force on an object that displaces in the same direction of the force

Question 7

How to calculate work

Answer 7

Force x displacement

Question 8

How to calculate work when it doesn’t displace in the same direction as the force applied

Answer 8

Applied force x cos theta x displacement

Question 9

When is there no work done

Answer 9

No displacement, no work, theta is 90, when the work is perpendicular to the objects displacement

Question 10

How to calculate kinetic energy

Answer 10

1/2 x mass x speed squared

Question 11

Work energy principle

Answer 11

The net amount of mechanical work done on an object equals the objects change in kinetic energy

Question 12

How to calculate net work

Answer 12

1/2 x mass x final speed^2 - 1/2 x mass x initial speed^2

Question 13

Gravitational potential energy

Answer 13

The amount of potential energy due to gravity with respect to a reference point

Question 14

How to calculate gpe

Answer 14

Mass x acceleration from gravity x height

Question 15

Energy

Answer 15

The capacity to do work or accomplish a task

Question 16

Sound energy

Answer 16

Produced by vibrations and travels by waves

Question 17

Radiant energy

Answer 17

Visible light and electromagnetic spectrum

Question 18

Nuclear energy

Answer 18

Nucleus of every atom has stored energy which can be transformed in nuclear reactions called fission and fusion

Question 19

Electrical energy

Answer 19

Electrons in an electric circuit

Question 20

Thermal energy

Answer 20

Atoms and molecules, more rapid movement = greater thermal energy

Question 21

Chemical potential energy

Answer 21

The energy stored in molecules bonds

Question 22

Law of conservation of energy

Answer 22

Total amount of energy in the universe is conserved, energy amount never changes, none is created or destroyed, just changed from one form to another

Question 23

Conservative force

Answer 23

Work is independent of the path taken (gravity, electric, magnetic)

Question 24

Non conservative force

Answer 24

Work is dependent on path (friction, air resistance)

Question 25

Efficiency

Answer 25

Ratio of useful energy output to the energy input

Question 26

Calculate efficiency

Answer 26

Energy output / Energy input x 100%

Question 27

Second law of thermodynamics

Answer 27

During the process of heat transfer and doing mechanical work, some thermal energy will leave the system without doing work. Thermal energy is always transferred from high temp to lower temp

Question 28

Power

Answer 28

The rate at which work is done

Question 29

Calculate power

Answer 29

Total energy / total time

Question 30

What is energy consumption measured in

Answer 30

Kwh

Question 31

Calculate cost

Answer 31

Rate (cents per kWh) x delta energy (in kwh)

Question 32

Kinetic molecular theory

Answer 32

All matter is made up of particles. Particles in hot objects move faster cause the have more kinetic energy and they spread out becoming less dense

Question 33

Thermal energy

Answer 33

Total kinetic and potential energy of the atoms or molecules of a subsrance

Question 34

Heat

Answer 34

Transfer of thermal energy from higher temp to lower temp

Question 35

Temperature

Answer 35

Average kinetic energy of the particles in a substance

Question 36

Three temp scales

Answer 36

Celsius, Fahrenheit, kelvin

Question 37

Calculate heat required for temp change

Answer 37

Q (heat transferred) = mass x specific heat capacity (J/Kg*C) x delta temperature (change in temp)

Question 38

Specific heat capacity

Answer 38

Amount of energy required to raise 1kg of a substance by 1 degree Celsius or kelvin

Question 39

The principle of thermal energy exchange

Answer 39

An equal amount of thermal energy transfers from an object at higher temp to a lower temp object until they reach thermal equilibrium

Question 40

Phase change

Answer 40

Requires a change in internal energy

Question 41

Latent heat of fusion

Answer 41

Q = mass x latent fusion. For melting and freezing

Question 42

Latent heat of vaporization

Answer 42

Q = mass x latent vaporization. For boiling/ vaporizing and condensation

Question 43

Which state has most kinetic energy

Answer 43

Gas, then liquids, then solids

Question 44

What is boiling point

Answer 44

When particles have enough kinetic energy to break away from each other

Question 45

Does temp change during state changes

Answer 45

Temperature stays the same during because thermal energy is being used, not kinetic energy

Question 46

Why does ice float

Answer 46

One of the few solids that are less dense than their liquid form (due to molecule chemical structure)