Q17DQ - University Physics with Modern Physics

Question

Time yourself while running up a flight of steps, and compute the average rate at which you do work against the force of gravity. Explain your answer in watts and in horsepower.

Step-by-Step Solution

Answer

Multiply the last result in watts by $\frac{1hp}{746W}$ to convert in horsepower.

Step 1: About work done by the man

The total work done by man is given by:

 W = mgh

The work done is expressed in terms of mass m, vertical height h, and g in SI units. 

Step 2: Calculation of Average rate or power

The rate at which work is done against the force of gravity is given by,

$\mathrm{P}=\frac{\mathrm{mgh}}{\mathrm{t}}\mathrm{watts}$  

Where   is the taken by man to run up the stairs.

Now, use the following conversion to express the rate in horsepower:

 $1hp=746W$ 

Thus, multiply the last result in watts by  $\frac{1hp}{746W}$ to convert in horsepower.