Question

A man weighing 60 kg goes up a staircase 5 m high in 20 seconds calculate his power in watt

Answer 1

Explanation:

P= mgh/ t

=60×10×5/20

=150 J/s

Answer 2

Given: The weight of a man is 60 kg.

He goes up a staircase of 5 m high.

Time taken by him is 20 seconds.

To find: The power of the man in watt.

Solution:

We know that, acceleration due to gravity = 10 $m/s^{2}$

The total work done by a body in covering a number of steps is calculated by the product of the weight of the body, acceleration due to gravity and the number of steps.

∴ Total work done = weight × acceleration × steps

                              $& =(60\times 10\times 5)Joules \\ & =3000Joules$

Power = $\frac{Work done}{Time taken}$

           $& =\left( \frac{3000}{20} \right)Watt \\ & =150Watt$

Hence, his power is 150 Watt.