GCSE Science/Energy in the Home

Work: When a force acts on an object and the object shows displacement, the force has done work on the object.

Two conditions need to be satisfied for work to be done: (i) A force should act on object (a) The object must be displaced

Unit of Work

→ Unit of work is Newton metre or Joule.

Negative, Positive and Zero Work

→ Work done by a force can be positive, negative or zero.

(i) Work done is positive when a force acts in the direction of motion of the body.

(ii) Work done is negative when a force acts opposite to the direction of motion of the body.

(iii) Work done is zero when a force acts at right angles to the direction of motion.

• -ve (negative) sign indicates that work is done against gravity.