AQA GCSE Kinetic energy

AQA GCSE Kinetic energy

Kinetic energy is the energy stored in a moving object.

Kinetic energy depends on mass of an object and the speed.

Kinetic energy, Ek = ½ x mass x speed2

Kinetic energy (Joules, J)

Mass (kilograms,kg)

Speed (m/s)

If mass increases, so will kinetic energy. They are directly proportional to each other. 

Graph showing the relationship between mass and kinetic energy as directly proportional
As the speed of an object increases then the velocity will increase by the square of the increase to the speed. If the speed is doubled, then the velocity will increase by a factor of 4. This is because 22 = 4 This effect happens becuase speed is a squared quantity in the kinetic energy equation.
Different equations for kinetic energy
You use the rearrangements directly, or if you want to use the triangle, you can. Just remember when using the triangle, if you want speed you will need to square root at the end.  The triangle will give v2. Unless you square root at final stage.

Practice questions

1.A ball of mass 0.1kg is travelling at a speed of 6m/s. Calculate the kinetic energy

2. A toy car with a mass of 60g is moving at 2m/s. Calculate its kinetic energy

3. Calculate the mass of a cannon ball that has a kinetic energy of 60,000J and a velocity of 10m/s

4. Calculate the velocity of a car if it has a kinetic energy of 45000J and a mass of 700kg. 

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Need more practice questions? See our worksheets.

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