Question

A body of mass 2kg moving on a horizontal surface with an initial velocity of 4ms${}^{-}$ ${}^1$ comes to rest in 2 seconds. If one wants to keep the body moving on the same surface with the velocity of 4 ms${}^{-}$ ${}^1$, the force required is :

• A. Zero
• B. 4 N
• C. 8 N
• D. 16 N

Answer 1

The correct option is B 4 N

From above figure

$A\to B$

u = 4m/s v=0 t=2sec a=?

$v=u+at$

$0=4+a\left(2\right)$

$a=-2m/s^2$

so,

force = ma

=$2\times 2=4N$

Hence (B) is the correct answer