P1 - Energy

Question 1

What is energy?

Answer 1

The capacity of something to do work.

Question 2

What is the law of conservation of energy?

Answer 2

Energy cannot be created or destroyed, only transferred into other stores.

Question 3

What is dissipation?

Answer 3

Transfer of energy into less useful forms.

Question 4

How is work done calculated?

Answer 4

Work done (j) = force (N) x distance (m)

Question 5

How is power calculated?

Answer 5

Power = work done ÷ time

ALSO,
Power = (force x distance) ÷ time

Question 6

What is power?

Answer 6

The rate at which energy is transferred / work is done.

Question 7

What does work done mean?

Answer 7

When a force causes an object to move through a distance, work is done on the object.

Question 8

What is efficiency?

Answer 8

The proportion of energy that is in a useful energy store after a change in a system.

Question 9

How is efficiency calculated?

Answer 9

Useful power/energy output
——————————————
Total power/energy input

Question 10

How is percentage efficiency calculated?

Answer 10

Useful power/energy output
—————————————— X 100
Total power/energy input

Question 11

What is temperature?

Answer 11

A measure of the average kinetic energy of particles in a substance.

NOT the thermal energy store of the substance.

Question 12

How does the mass of a substance effect the temperature change?

Answer 12

The greater the mass, the more energy is needed to increase the temperature.

Question 13

What are all the energy stores?

Answer 13

1. Thermal
2. Kinetic
3. Gravitational potential
4. Elastic potential
5. Chemical
6. Magnetic
7. Electrostatic
8. Nuclear

Question 14

What is the thermal energy store?

Answer 14

The total kinetic energy stored in all the particles of an object.

Question 15

What is the kinetic energy store?

Answer 15

The energy an object has because it is moving.

Question 16

How is kinetic energy calculated?

Answer 16

KE = 0.5 x m x v²

KE (j) = 0.5 x mass (kg) x speed² (m/s)

Question 17

What is the gravitational potential energy store?

Answer 17

Energy stored in an object due to its position in a gravitational field.

Question 18

How is gravitational potential energy calculated?

Answer 18

GPE = mgh

GPE = mass (kg) x gravitational field strength (N/kg) x height (m)

Question 19

What is the gravitational field strength on earth?

Answer 19

9.8

Question 20

What is the elastic potential energy store?

Answer 20

The energy an object has when it is stretched or compressed.

Question 21

How is elastic potential energy calculated?

Answer 21

EPE = 0.5 x k x e²

EPE = 0.5 x spring constant (N/m) x extension² (m)

Question 22

What is the chemical energy store?

Answer 22

The energy stored in fuels, food, or batteries that can be transferred by chemical reactions.

Question 23

What is the magnetic energy store?

Question 24

What is the electrostatic energy store?

Answer 24

Energy stored when repelling charges move closer together
OR when attracting charges pull further apart.

Question 25

What is the nuclear energy store?

Answer 25

Energy stored in the nucleus of an atom.

Question 26

What is the law of conservation of energy?

Answer 26

Energy cannot be created or destroyed, only transferred into other stores.

Question 27

What are all the energy transfers?

Answer 27

electrically, by heating, mechanically and by radiation.