Question

A man whose weight is 500N moves up 15 steps each of height 15cm in 40 seconds of time.Calculate the power used in climbing those stairs.

Answer 1

Solution:

Given values:
Force, f or mg = 500 N;
Time, t = 40 sec;
Height, h = 15*15= 225 cm (15 steps with height of 15 cm per steps)
h = 2.25 m;

Then,


$$\begin{gathered} Workdone=mgh \\ W=500x2.25(\mathit{f}\mathit{o}\mathit{r}\mathit{c}\mathit{e}\mathbf{}\mathbf{=}\mathbf{}\mathit{m}\mathit{g}\mathbf{}\mathbf{=}\mathbf{}\mathbf{500}\mathit{N}) \\ W=1125Joule; \\ Now, \\ Power=\frac{Workdone}{Time} \\ P=\frac{1125}{40} \\ \mathit{P}\mathbf{}\mathbf{=}\mathbf{}\mathbf{28}\mathbf{.}\mathbf{125}\mathbf{}\mathit{W}\mathit{a}\mathit{t}\mathit{t}\mathit{s} \end{gathered}$$