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Question:

A body is moved along a straight line by a machine delivering constant power. The distance travelled by the body in time t is proportional to?

t1/2

t

t3/2

t2

Solution:

Power is rate of doing work, P=W/t=F.s/t=F.v=(ma)(at)=ma²t ⇒a²t=P/m=constant
Also s=1/2at² ⇒s²=1/4a²t⁴=constant.t³ ⇒s∝t³/²