Question

why school bags have wide straps?

Answer 1

pressure is equal to force by area.So area and pressure are indirectly proportional that is more the area less the pressure.So wide straps in school bags makes them aquire much area to reduce the pressure on our shoulders.

Answer 2

as we know that pressure is inversely proportional to area. Means increased area results in decreased pressure. so having wide straps in bags increases the area and thus the pressure is decreased and our bag is lighter.