411 REFERENCE · Wikibooks
GCSE Science/Energy in the Home
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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.