Q. 76

# A man is instructed to carry a package from the base camp at B to submit A of a hill at a height of 1200 metres. The man weighs 800 N and the package weighs 200 N. If g = 10 m/s^{2},

(i) How much work does man do against gravity?

(ii) What is the potential energy of the package at A if it is assumed to be zero at B?

Answer :

(i) Weight of the man = 800N

Weight of the package = 200N

Total weight = 800 + 200 = 1000N

Height of the hill = 1200m

g = 10m/s^{2}

Work done = mass × height × g

= 10 × 1200 × 1000

= 12, 00, 000 J

= 12 × 10^{5} J

(ii) Given, Weight of the package (mg) = 200N, h = 1200m

P.E = m x g x h

= 200 × 1200 × 10

= 24 × 10^{5} J

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