Question
Tue September 11, 2012 By: Prajitha P
 

When we apply a force on an object and if the object shows a displacement in the direction of the force then it is said that a work is done,but if the direction of displacement is opposite to the direction of force then it is said that work is not done.Why is it so?

Expert Reply
Wed September 12, 2012
If the direction of displacement is opposite to the direction of force then it is said that work is  done but negative ie work is done on the system to overcome that force effect and move.
 
simillarly, when a stone is thrown upward, that force is used to overcome the effect of gravitational pull of earth and the stone moves upward,ie displacement in opposite direction of effective force on the object ie gravitational force.
Here gravitational force does negative work.
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