Question

A student who weighs 557 N climbs a stairway (vertical height of 4.5 m) in 29 s.(a) How much work is done?answer in J(b) What is the power output of the student?answer in W

Answer 1

Given,

The weight of the student, w=557 N

The height of the stairway, h=4.5 m

Time interval in which the student climbs the stairway, t=29 s

(a) The work done is given by the difference in the initial and final potential energy,

That is

$W=wh$

On substituting the known values,

$\begin{gathered} W=557\times4.5 \\ =2506.5\text{ J} \end{gathered}$

Thus the work done by the student in climbing the stairway is 2506.5 J

(b) The power is given by the time rate of work done.

That is

$P=\frac{W}{t}$

On substituting the known values,

$\begin{gathered} P=\frac{2506.5}{29} \\ =86.43\text{ W} \end{gathered}$

Thus the power output of the student is 86.43 W