Question

Problem 1.32. A man cycles up a hill, whose slope is
1 in 20 with a velocity of 6.4 km h-1 along the hill. The weight
of the man and the cycle is 98 kg. What work per minute is he
doing? What is his horse power?
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Answer 1

Answer:

Explanation:

Given A man cycles up a hill, whose slope is

1 in 20 with a velocity of 6.4 km h-1 along the hill. The weight

of the man and the cycle is 98 kg. What work per minute is he

doing? What is his horse power?

We know that v = 6.4 km /hr = 6.4 x 1000 / 3600 = 64/36 = 16/9 m / s

Since he cycles up the hill we get

F = mg sin θ

Given slope is 1 in 20, so sin θ = 1/20

We know that

Power = F x V

         = mg sin θ x V

          = 98 x 9.8 x 1/20 x 16/9

power = 85.368 Watts

We know that  1 horse power = 746 watts

 746 watts = 1 horse power

So 85.368 watts = 0.1144 horse power

Now we need to find work done

So power = w / t

    W = P x t

        = 85.368 x 60

    W = 5122.08 J

Answer 2

5122.08 .............