Question

(a) Define pressure. What is the relation between pressure, force and area? State units in which pressure is measured.

(b) Explain why school bags are provided with wide straps to carry them.

Answer 1

(a)

Pressure is defined as the force applied perpendicular to the surface of an object per unit area over which that force is distributed.​ ​​​​​​

$P\alpha \text{Force acting}\left(F\right)P\alpha \frac{1}{\text{Area}\left(A\right)}$

After combining both equations

$P=\frac{F}{A}$

Units of pressure:

The SI unit of pressure is the pascal (Pa) which is defined as a force of one Newton per square meter or $N{m}^{-2}$. Other units are atm and torr.

The conversion between atm, Pa, and torr is as follows: $1atm=101325Pa=760torr$.

(b)

1. School bags are provided with wide straps because it is easy to carry bags with wide straps.
2. A wider strap distributes the force throughout a greater surface area or for a wider strap the pressure will be less.