Question:
A man moves on a straight horizontal road with a block of mass 2kg in his hand.If he covers a distance of 40m with an acceleration of 0.5m/s2.Find the work done by the man on the block during the motion?Explain..
Answer:
As there is horizontal motion, the work done is kinetic energy. We know KE = ½ mv2
m = 2Kg; a = 0.5 m/s2 ; s = 40m But we need v to calculate the KE
Hence, we can use the laws of motion.
S = ut + ½ at2 Here u = 0
Hence, s = ½ a t2
40 = ½ (1/2) t2
t = 4(10)1/2 ----------------Eqn (1)
v = u + at Here u = 0 and we get t from Eqn (1)
v = at = ½ * 4(10)1/2 = 2 (10)1/2 ----------------Eqn (2)
KE = ½ mv2 = ½ * 2 * 2 * (10)1/2 * 2 * (10)1/2 = 40J
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