# Kinetic, Gravitational pot and elastic pot. with exam style questions

- Created by: jelomo
- Created on: 20-08-20 11:59

*Energy Stores and Systems*

When energy is transferred to an object, the energy is stored in one of the object's energy stores. **Energy is measured in Joules.** The energy stores you need to know are:

- Thermal
- Kinetic
- Gravitational potential
- Elastic potential
- Chemical
- Magnetic
- Electrostatic
- Nuclear

**A "system" in physics means a single object or a group of objects.** When a system changes, energy is transferred. Energy can be transferred by heating objects or by doing work. **Work done is the same as energy transferred**; work can be done when current flows or by a forc moving an object.

*Kinetic Energy*

Movement means that there is energy in an object's kinetic energy store. **Energy is transferred to the object when it speeds up and energy is transferred away when an object slows down.** The equation for kinetic energy is:

**Ek(J) = 0.5 x mass(kg) x speed^2 (m/s^2)**

An example question:

**A car has a mass of 2500kg and is travelling at 30m/s. Calculate the energy in its kinetic energy store.**

1) Write out the equation and rearrange if necessary.

2) Substitute the numbers into the equation.

3) Calculate…

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