Question

A force makes a stationary body of mass $25kg$ to move $60m$ in $10s$. Find the magnitude of this force.

• A. $25N$
• B. $30N$
• C. $35N$
• D. $40N$

Answer 1

The correct option is B $30N$

Given: mass of object $m=25kg$, time $t=10s$, displacement $s=60s$, and initial velocity $u=0$.
Let the acceleration of the body be $a$ and magnitude of the force be $F$

Using the first equation of motion
$s=ut+\frac{1}{2}a{t}^2\Rightarrow a=\frac{2(s-u)}{t^2}=\frac{2\times (60-0)}{{10}^2}=\frac{120}{100}=1.2m{s}^{-2}$

Using Newton's second law of motion,
$F=ma=25\times 1.2=30N$
Thus, the magnitude of force is $30N$.