Question

bi) It takes 20 second for a persona of mass bokg
to climb up the stairs, while another person
of same mass does the same in 30 sec.(i.) compare
the work done
(ii) compare the power developed by the persons
A and B.​

Answer 1

Given:-

• Let, the height attained by both person = h
• Let, the mass of person A be M

• And , let the mass of person be m'

• Time taken by persons A (t) = 20s

• Time taken by person B (t') = 30s

To Find:-

• Work done (W)
• Power (P) developed by Person A and B

Solution:-

As we know that the acceleration due to gravity is 9.8m/s². And here the person works against gravity .So

→ W= mgh

Work done for Person A

Substitute the value we get

→ W = M ×9.8× h

→ 9.8×M×h ...................(i)

Now Work done For Person B

→ W' = mgh

Substitute the value we get

→ W' = m'×9.8×h.

→ W' = 9.8×m×h..................(ii)

Here ,

W = W'

→ 9.8×M×h = 9.8×m'×h

→ M = m'

And Now We have to calculate the Power developed by Both Person A and B.

Similarly

→ P = mgh/t

Power developed by Person A

→ P = M× g ×h/20

→ P = g×M×h/20

And Power developed by person B

→ P' = m'×g×h/30

→ P' = g×m'×h/30

P = P'

→ g×M×h/20 = g×m'×h/30

→ 20 = 30

→ 2 = 3

∴The Power developed by person A and B is 3:4 watt.