Question

The force is perpendicular to the ______.

Answer 1

Step 1: Force

1. According to Newton's second law of motion, force is directly proportional to the rate of change of momentum per unit of time.
2. If $\overrightarrow{p}$ is the momentum and $t$ is the time taken, then force can be given as $\overrightarrow{F}\propto \frac{d\overrightarrow{p}}{dt}$.
3. We know that $\overrightarrow{p}=m\overrightarrow{v}$, where $\overrightarrow{v}$ is the velocity.
4. $\therefore \overrightarrow{F}=\frac{d}{dt}\left(m\overrightarrow{v}\right)=m\frac{d\overrightarrow{v}}{dt}$
5. We know that acceleration $\overrightarrow{a}=\frac{d\overrightarrow{v}}{dt}$. Hence, $\overrightarrow{F}=m\overrightarrow{a}$.
6. The derived unit of force is $kgm{s}^{-2}$ or $N$.

Step 2: Pressure

1. Pressure is defined as the force applied perpendicular to a surface per unit area.
2. If $F$ is the force applied to a body and $A$ is the area upon which the force is applied, then the pressure can be given as, $P=\frac{F}{A}$
3. The derived unit of pressure is $N{m}^{-2}$ and the SI unit is $Pa$.

Hence, the force is perpendicular to the pressure.