Work and power

Which of these increases the kinetic energy of a car the most?

Because velocity is squared in the equation for kinetic energy, doubling the velocity gives a bigger increase.

What amount of gravitational potential energy would be gained when a one kilogram book is carried up a flight of stairs 15 metres tall?

Gravitational potential energy = weight x height. One kilogram has a weight of ten newtons. This is multiplied by 15 metres to give 150 joules.

How do we calculate gravitational potential energy on Earth?

Gravitational potential energy is calculated as weight multiplied by height.

How do we calculate power?

Power is calculated as work done divided by time. More work or less time means greater power.

How do we calculate kinetic energy?

The formula for kinetic energy is: 0.5 x m x v2. The units are joules.

What is the main energy transfer in a rollercoaster?

The main energy transfer in a rollercoaster is gravitational potential to kinetic as it falls.

What are the units for power?

The units for power are watts. These are the same as joules per second.

What are the units for work done?

The units for work done are joules. These are the same units as for energy.

What would the work done be when a one kilogram book is carried up a flight of stairs 15 metres tall?

Work done = force x distance moved. One kilogram has a weight of ten newtons. This is multiplied by 15 metres to give 150 joules.

How do we calculate work done?

Work done is calculated as force multiplied by distance moved. A larger force or distance means greater work.