Question

A body of mass $2kg$ is at rest. What should be the magnitude of force which will make the body move with a speed of $30m/s$ at the end of $1s$?

Answer 1

Step1: Given data

The mass of the body is $2kg$.

The body was at rest, $initialvelocity,u=0m/s$

The body moves with a speed of $30m/s$ at the end of $1s$ i.e., $finalvelocity\left(v\right)=30m/sandtime\left(t\right)=1sec$

Step2: Formula used

According to Newton’s second law of motion, the magnitude of the applied force on a body is equal to the product of its mass and acceleration.

$F=m\times a[whereF=force,m=mass,a=acceleration]$

Step3: Calculating force

We say that a body accelerates when an imbalanced force is applied to it.
The rate of change in velocity of a body with respect to time is known as acceleration.

$$\begin{gathered} a=\frac{(v-u)}{t}[wherea=acceleration,v=finalvelocity,u=intialvelocity,t=1sec] \\ a=\frac{(30-0)}{1} \\ a=30m/s^2 \end{gathered}$$

Therefore $a=30m/s^2$

Substituting the value of mass and acceleration in the formula

$$\begin{gathered} F=m\times a \\ F=2\times 30 \\ F=60N \end{gathered}$$
Hence, the magnitude of the force that will make the body move is $60N$.