SP8: Energy - Forces Doing Work

Question 1

SP8a
1) Describe some ways in which the energy of a system can be changed.
2) What is work done?
3) Recall and use the equation linking work done, force and distance.

Answer 1

1) The energy of a system changes when energy is transferred to or from the system.
- Electrical equipment: charges moving due to a potential difference.
- Heating: due to temperature difference caused electrically or by chemical reaction.
- Through work done by forces
2) Work is done when energy is transferred by a force.
3) Work done (J) = Force (N) x Distance moved (m)

Question 2

SP8a
1) Explain what power means.
2) Recall and use the equation linking power, work done and time.

Answer 2

1) Power is the rate at which energy is transferred. It is also the rate at which work is done. Power is measured in Watts (W).
2) Power (W) = work done (J) / time taken (s)