Question

A body of mass 2 kg having a velocity of 2 m/s is brought to rest within a distance of 2 metres. Find the magnitude of the force acting on the body.

• A. 8 N
• B. 1 N
• C. 4 N
• D. 2 N

Answer 1

The correct option is D 2 N

Let the acceleration be ‘a’.
From the third equation of motion,
$v^2$ - $u^2$ = 2as
a = $\frac{v^2-u^2}{2s}$
a = $\frac{0^2-2^2}{2\times 2}$ (v = 0 m/s as the object is coming to rest.)
a = -1 $m{s}^{-2}$

From Newton’s second law of motion,
F = ma
F = 2 x (-1) = -2 N
(The negative sign implies that the force is acting in a direction opposite to the motion of the object.)