Section 2 - General Physics: Energy and Pressure

Question 1

All 7 energy store

Answer 1

Kinetic - anything moving
Gravitational potential - anything that fall
Chemical - anything that releases energy through chemical reaction
Elastic - anything stretched
Nuclear - Atomic nuclei release energy from this in nuclear reactions
Electrostatic - two charges that attract or repel
Thermal - any object, hotter objects have more

Question 2

Principle of conservation of energy

Answer 2

The principle of conservation of energy states that energy can be stored, transferred from one store to another, or dissipated - but it can never be created or destroyed.

Question 3

4 ways of energy transfer

Answer 3

1. Mechanically - work is done by a force acting on an object
2. Electrically - work is done by an electric current flowing
3. By waves - energy transferred by waves like sound and light
4. By heating - energy transferred from a hotter to colder object

Question 4

Kinetic energy equation - energy whilst moving

Answer 4

Depends on mass and speed

Kinetic energy = 0.5 x mass(kg) x speed(m/s) squared
Ek = 0.5mv^2

Question 5

GPE equation - raised objects store energy

Answer 5

Change in GPE = mass(kg) x gravity(9.8N/kg) x change in height(m)
Change in GPE = mgh

Question 6

What is work

Answer 6

Work done is equal to energy transferred

Question 7

Work done formula

Answer 7

Work done = force x distance = energy transferred
W = Fd = change in E

Question 8

Power

Answer 8

Power is the work done or the energy transferred per unit time

Question 9

Power equation - energy transfer

Answer 9

Power(W) = energy transferred(J) / time taken(s)
P = E change / time

Question 10

Efficiency

Answer 10

The efficiency of a process or device is a measure of the proportion of the input energy that is transferred usefully

Question 11

Efficiency equation

Answer 11

Efficiency = useful energy output / total energy input x 100