Question
Sun March 11, 2012 By: Deepak Garg

Given below are a few situations, study then and state in which of the given cases work is said to be done. Give reason for your answer:- (i) A Person pushing hard a huge rock does not move ? (ii) A bullock pulling a cart up to 1 km on road ? (iii) A girl pulling a trolley for about 2 km distance ? (iv) A person standing with a heavy bag on his head ?

Expert Reply
Sun March 11, 2012
(i) A Person pushing hard a huge rock does not move - no displacement, so no work.
 (ii) A bullock pulling a cart up to 1 km on road - force is applied and there is displacement also, so work is done.
(iii) A girl pulling a trolley for about 2 km distance -  force is applied and there is displacement also, so work is done.
(iv) A person standing with a heavy bag on his head - no displacement, so no work.


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