Question

A man is riding on a cycle with velocity 7.2 km/hr up a hill having a slope 1 in 20. The total mass of the man and cycle is 100 kg. The power of the man is

• A. 200 W
• B. 175 W
• C. 125 W
• D. 98 W

Answer 1

The correct option is D 98 W

$V=7.2\frac{km}{h}=7.2\times \frac{5}{18}=2m/s$
Slope is given 1 in 20
$\therefore sin\theta =\frac{1}{20}$
When man and cycle moves up then component of weight opposes it motion i.e. F = mg sin $\theta$
So power of the man P = F $\times$ v = mg sin $\theta$ $\times$ v
$=100\times 9.8\times (\frac{1}{20})\times 2=98Watt$