Question

A man cycles up a hill whose slope is 1 in 20 with a velocity of 6.4 kmh^-1 along the hill. The weight of the man and the cycle is 98 kg. What work per minute is the man doing? What is his horse power?

Answer 1

Explanation:

The slope of incline is 1 in 20.

1

This means, sin 20 where is the angle of inclination with the horizontal,

v = 6.4km h 6400ms 1 -1 6.4 × 1000 60 × 60 - ms 1 = -

3.600

16 9 ms -1

?

m = 98kg

t = 1min - 60s

W = ?, H.P.

As force applied in moving up the incline is F = mg sin 0

As Power force x velocity

:. P = mg sin 0× v

1 16 P = 98 x 9.8 x X watt 20 9

As 1 horse power = 746watt... Horse power of the person

98 x 9.8 16 X 20 9 × 746 = 0.114

As work done = power x time 98 x 9.8 x 16 20~ 0 ... in t = 60s, W: X

60=5122.1J

*Hope it will help you*

Thanks