Energy

Question 1

What is energy measured in?

Answer 1

Joules (J)

Question 2

What are the five energy stores?

Answer 2

Thermal
Elastic potential
Chemical potential
Gravitational potential
Kinetic

Question 3

Describe a thermal energy store.

Answer 3

All objects have thermal energy. It is the energy a substance has due to its kinetic energy (movement) of its particles. The more thermal energy a material has, the hotter it is.

Question 4

Describe an elastic potential energy store.

Answer 4

When materials are stretched and have the potential to return to their original shape they store elastic potential energy. The same goes for squashed materials.

Question 5

Describe a chemical potential energy store.

Answer 5

A type of stored energy that is released by chemical reactions. Fuels, foods and batteries all contain chemical energy.

Question 6

Describe a gravitational potential energy store.

Answer 6

Any object in a gravitational potential field has gravitational potential energy due to its position in that field.

Question 7

Describe a kinetic energy store.

Answer 7

Kinetic energy is the energy an objet has because it is moving.

Question 8

Since energy cannot be created or destroyed, what can it do?

Answer 8

It can be transferred.

Question 9

What are energy stores classified as in energy transfers?

Answer 9

Useful or not useful.

Question 10

what is the formula for work done?

Answer 10

Work done (J) = force applied (N) x distance moved along line of action of force (M)
W=FxS

Question 11

What is the formula for weight?

Answer 11

Weight (N) = mass x GPE

Question 12

What is the formula for mass?

Answer 12

Kinetic Energy
———————
1/2 x velocity^2

Question 13

What is the formula for kinetic energy?

Answer 13

KE (J) = 1/2 x mass x velocity^2

Question 14

What is the formula for velocity?

Answer 14

___________
|kinetic energy
|——————
| 1/2 x mass

Question 15

What is the formula for elastic potential energy?

Answer 15

E (EPE) = 1/2 x k (spring constant) x e^2 (extension^2)

Question 16

What is the formula for power?

Answer 16

Energy transferred/time

Question 17

What is the formula for efficiency?

Answer 17

(Useful energy output/total power input)x100

Question 18

What happens to an elastic object when the forces deforming it are removed?

Answer 18

Regains original shape.

Question 19

Define specific heat capacity.

Answer 19

How many joules of heat energy are needed to raise the temperature of each kilogram by 1’C.

Question 20

What is the formula for change in energy?

Answer 20

🔺E = m (mass kg) x c (specific heat capacity J/kg’C) x 🔺Θ (change in temperature ‘C)

Question 21

What is the Law of Conservation of Energy?

Answer 21

Energy = energy cannot be created or destroyed.

Question 22

Define dissipated energy.

Answer 22

Wasted energy spreading into the surroundings.

Question 23

Define conduction.

Answer 23

Energy transferred through collisions between neighbouring vibrating particles. Only takes place in solids.

Question 24

Define convection.

Answer 24

Energy transferred through rising regions of a fluid. Takes place in liquids and gases.

Question 25

Define radiation.

Answer 25

Energy transferred by electromagnetic radiation. Takes places through free spaces.

Question 26

Define evaporation.

Answer 26

Energy transferred away from surface of a liquid by escaping high energy particles.

Question 27

Define condensation.

Answer 27

Energy transferred to a solid by gas forming a liquid on the surface.

Question 28

What is the formula for specific heat capacity?

Answer 28

🔺E / m x 🔺degrees