A girl of weight 440 N climbs up a rope through a height of 7 m in 20 s. The power expended by the girl is:

Question

Question

This question was previously asked in

RRB ALP Electrician 22 Jan 2019 Official Paper (Shift 2)

Answer 1

Concept:

Power is defined as the rate of doing work.
This unit of power is Watt (W)
If a device does a work (W) in time (t), then its power (P) is given by the formula,
- \(P = \frac Wt\)
Work is defined as when the force acting on a body displaces the body in its direction.
We can calculate work (W) using the formula W = F × s
where, F is the force applied, and s is the displacement caused by the force along its direction.

Calculation:

Given, weight, F = 440 N, height, s = 7 m, Time, t = 20 s

Work, W = 440 × 7

Now, power \(P = \frac Wt \)

\(\Rightarrow P = \frac {440 \times 7}{20} \)

P = 154 W