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

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…