Answers to Practice Questions

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

Kinetic energy, E_k = ½ x mass,m x speed,v²

E_k = ½ x 0.1 x 6²

E_k = 1.8J

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

The 60g needs to be converted into kilograms. 60g = 0.06kg

Kinetic energy, E_k = 1/2 x mass,m x speed,v²

E_k = ½ x 0.06 x 2²

E_k = 0.12J

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

Kinetic energy, E_k = ½ x mass,m x speed,v²

Rearrange this equation to make mass the subject: