Question

There are $2$ school bags A & B. Bag A is provided with a broader strap while bag B is provided with a thinner strap. For the same load, a school boy likes bag A as he is comfortable with it, but with bag B he develops a pain in his shoulders. Why?

Answer 1

Pressure

Since, the pressure is the force per unit area

$$\begin{gathered} \mathrm{i}.\mathrm{e}.\mathrm{P}=\frac{\mathrm{f}}{\mathrm{a}} \\ \Rightarrow P\propto \mathrm{a} \end{gathered}$$

therefore, in bag A as the straps are broader, the pressure developed would be less than B for the same load.

Therefore, the person who lifts bag B will develop a pain in his shoulders.