Physics Equations

Question 1

Kinetic Energy full equation

Answer 1

Kinetic energy = mass x velocity² x 0.5

Question 2

Kinetic energy equation with letters

Answer 2

Ek = 1/2 x mv²

Question 3

Units for:

Kinetic energy
Mass
Velocity

Answer 3

Kinetic energy = J//joules
Mass = kg/kilograms
Velocity = m/s / metres per second

Question 4

Example of kinetic energy

Answer 4

Moving car - it moves forwards and backwards which means it uses kinetic energy

Question 5

Elastic potential energy full equation

Answer 5

Elastic potential energy = 0.5 x spring constant x extension²

Question 6

Elastic potential equation with letters

Answer 6

Ee = 1/2 x ke²

Question 7

Units for elastic potential energy equation:

Elastic potential energy
Spring constant
Extension

Answer 7

Elastic potential energy = J/joules
Spring constant = N/m / newtons per metre
Extension = m/metres

Question 8

Example of elastic potential energy

Answer 8

A stretched spring = when the spring stretches it is using elastic potential energy by being stretched

Question 9

Gravitational potential energy full equation

Answer 9

Gravitational potential energy = mass x gravitational field strength x height

Question 10

Gravitational potential energy equation with letters

Answer 10

GPE/Ep = m x g x h

Question 11

Units for gravitational potential energy equation:

Gravitational potential energy
Mass
Gravitational field strength
Height

Answer 11

Gravitational potential energy = J/joules
Mass = kg/kilograms
Gravitational field strength = N/kg / newtons per kilograms
Height = m/metres

Question 12

Example of gravitational potential energy

Answer 12

Throwing a ball in the air = when the ball is thrown the gravity pulls it back down to the earth

Question 13

Change in thermal energy full equation

• do not need to know off by heart for the test

Answer 13

Change in thermal energy = mass x specific heat capacity x change in temperature

• do not need to know off by heart for the test

Question 14

Change in thermal energy equation with letters

• do not need to know off by heart for the test

Answer 14

Et = m x c x T

• do not need to know off by heart for the test

Question 15

Units for change in thermal energy equation:

Change in thermal energy
Specific heat capacity
Change in temperature

Answer 15

Change in thermal energy = J/joules
Specific heat capacity = J/kg/degrees C
Change in temperature = degrees C

Question 16

What is the law of conservation of energy?

Answer 16

Energy cannot be created or destroyed, it can only be converted from one form to another

Question 17

What is dissipation?

Answer 17

Loss of energy through its conversion into heat.

Question 18

Describe what a system is

Answer 18

It is an object or group of objects

Question 19

What is wasted energy?

Answer 19

Wasted energy is energy that is not usefully transferred or transformed

Question 20

What is efficiency?

Answer 20

Efficiency is a measure of how much USEFUL energy you get out of an object from the energy you put INTO it.

Question 21

What does inefficient and efficient mean?

Answer 21

Efficient = LOTS of USEFUL energy
Inefficient = NOT MUCH USEFUL energy

Question 22

If a light bulb has electricity put into it what are the outcomes and which one is useful and which one is wasted energy?

Answer 22

Electricity ➡️light + heat

Light is the useful part and the heat is the wasted energy. the heat is dissipated to the surroundings

Question 23

If a vacuum cleaner has electricity put into it what are the outcomes and which one is useful and which one is wasted energy?

Answer 23

Electricity ➡️GPE + heat + sound

The heat and sound are the wasted energies but the GPE is needed to suck dirt off the surfaces.

Question 24

If a TV has an input of 200J of energy and 80J of energy is used for light and another 80J of energy is used for heat, work out how much energy is used for sound and identify the wasted and useful energies.
Is the TV efficient based on how much energy is wasted and needed?

Answer 24

40J of energy is used for sound. The useful energies are the sound and light so we can see and hear the TV. The energy is wasted on heat as it is not needed.
The TV is efficient as less energy is used on the wasted energy than the sum of both the needed energies.

Question 25

What is the equation to work out mass?

Answer 25

m = ke / 1/2 x v²

Question 26

What is the equation to work out velocity?

Answer 26

v = √ke/½ x m

Question 27

What is kinetic energy?

Answer 27

Any moving object will have kinetic energy. It is the store for any movement except up. An example is a car.

Question 28

What is gravitational potential energy?

Answer 28

Gravitational potential energy is energy stored in an object moving upwards. An example is throwing something in the air.

Question 29

What is thermal energy?

Answer 29

Thermal energy is the store of heat. When you heat something up you transfer thermal energy and this changes the temperature of the object. How quickly something heats up depends on its mass. The smaller the amount the shorter the time it will take to heat up.
An example of this is a radiator as it gives out heat and is hot.

Question 30

What is the chemical energy store?

Answer 30

The chemical energy store is anything that runs on food or energy. An example of this is a toy car as it uses a battery to operate.

Question 31

What is the nuclear store?

Answer 31

The nuclear store is if something has a nucleus or nuclear in the name. It is also the forces between particles. Examples of this are a nuclear bomb or an atom.

Question 32

What is the elastic potential store?

Answer 32

The elastic potential store is anything that can, be or does stretch. Examples of this are an elastic band or a spring.

Question 33

What is the magnetic energy store?

Answer 33

The magnetic energy store is something that will attract or repel. An example is a magnet..