Question

Why is it difficult to hold a school bag having a strap made of a thin and strong string?

Answer 1

Pressure:

1. The force acting per unit area is called pressure.
2. We know that, $Pressure=\frac{Force}{Area}.$
3. Pressure is inversely proportional to the area.
4. larger the surface area less will be the pressure and vice versa.
5. In the case of a thin strap, the contact surface area is very small which produces large pressure on the shoulder.

Hence, to reduce pressure on the shoulder the strap of the school bag is made thick.