Summary Energy - key notes and concepts - AQA GCSEs - great revision resource

Physics gcse unit 1 - Energy - Key notes


ENERGY STORES : INTRODUCTION

- A system is an object or group of objects
- When a system changes, the way the energy is stored also changes

EXAMPLES:

- A ball rolling and hitting a wall: the system is the moving ball and when it hits the
wall, some of the kinetic energy in the ball is transferred as sound.

ENERGY STORES : FORMULAS

● Kinetic energy :

- Ek = ½ mv²
- Here, m is the mass in kilograms (kg) ,v is the speed, in metres per second (m/s) ,
and the kinetic energy (Ek) is in joules ( J)

● Elastic potential :

- Ee = ½ ke²
- Here, Ee is the elastic potential energy in joules (J), k is the spring constants in
newtons per metre ( n/m) and e is the extension in metres (m)

● Gravitational Potential energy

- Ep = m g h
- Here, Ep is the gravitational potential energy in joules (J) , g is the gravitational field
strengths ( 9.8) in newtons per kilogram ( n/kg) and h is the height in metres (m)

SPECIFIC HEAT CAPACITY

Specific heat capacity is the energy required to raise 1kg of a substance by 1℃

Energy = mass x specific heat capacity x temperature change

( E = mc∆t )

- Where the change in thermal energy,( ∆E ) is in joules,( J,)
- Mass (m) in kilograms (kg)
- the specific heat capacity (c) in joules per kilogram per degree Celsius, (Jkg−1°C−1)
- and the temperature changes (∆T) in degrees Celsius, (°C.)