Question

On an object of mass $1$ kg moving along x-axis with constant speed $8$ m $2$N is applied in positive y-direction. Find its speed after $4$ seconds.

• A. $8\sqrt{2}$
• B. $4$
• C. $10\sqrt{2}$
• D. $5$

Answer 1

The correct option is A $8\sqrt{2}$

Consider the problem

Speed along $x-axis$ is $v_x=8m/s$

Mass, $m=1kg$

Force applied, $F_y=2N$

Acceleration, $a_y=\frac{F}{m}=\frac{2}{1}=2m/s^2$

Now along $y$ the body starts moving after application of force.

initial velocity along $y,u_y=0$

so,

$v_y=u_y+a_{y}t$

therefore

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

$v_y=8m/s$

Now,

magnitude of resultant velocity is

$v=(v_x^2+v_y^2{)}^{\frac{1}{2}}=(8^2+8^2{)}^{\frac{1}{2}}$

$=8\sqrt{2}m/s$