(a) Give two conditions for work to be done. (b) What is the work done by frictional force on an object when dragged along a rough surface ? (c) Relate power and work. (d) A machine does 1960 joule of work in 4 minutes. What is the power?


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(a) A force should act on the body and it should have displacement.
(b) Negative.
© P = work/time
(d) Given W = 1960 J, t = 4 min = 4 x 60 = 240 s,
P = ?
P = W/t = 1960/240 = 8.2 W