Question

A force causes a stationary object of mass $10kg$ to move $45m$ in $6s$. Find the magnitude of this force.

• A. $50N$
• B. $10N$
• C. $25N$
• D. $30N$

Answer 1

The correct option is C $25N$

Given: mass of object $m=10kg$, displacement $s=45m$, initial velocity $u=0$, and time $t=6s$
Let $a$ be the acceleration caused by the force of magnitude $F$.

Using second equation of motion:
$s=ut+\frac{1}{2}a{t}^2\Rightarrow a=\frac{2(s-ut)}{t^2}=\frac{2\times (45-0)}{6^2}\Rightarrow a=2.5m{s}^{-2}$

Using Newton's second law of motion:
$F=ma=10\times 2.5=25N$
Thus, the magnitude of force is $25N$