Question

A body of mass 2 kg is moving towards north with a speed of $4{ms}^{-1}$. A force of 4 N is applied on it towards west. Displacement of the body 2 seconds after the force is applied

• A. $4\sqrt{5}m$
• B. $4\sqrt{2}m$
• C. $5\sqrt{4}m$
• D. $5\sqrt{2}m$

Answer 1

The correct option is A $4\sqrt{5}m$

Displacement due north will be $X_N=u_{N}t=4\times 2=8m$

Acceleration due West will be $a=\frac{4N}{2kg}=2m/s^2$

so the displacement due $west$ will be $X_W=u_{W}t+\frac{1}{2}a{t}^2=0+2^2=4m$

As $north$ and $west$ are $perpendicular$ to each other so net displacement will be $X=\sqrt{X_N^2+X_W^2}=\sqrt{64+16}$

or $X=4\sqrt{5}meter$