Question

An object of mass 2kg moving with velocity 10 m/s,at t - 0 sec ,a retarding force of 4N acts on it for 10sec. What will be its velocity and displacement after 10 sec.

Answer 1

Given
Mass of object, m=2 kg
Initial velocity, u=10 m/s
Retarding force, F=-4 N
Time, t=10 sec
Using,
F=ma
or a=F/m=-4/2$=-2\mathrm{m}/{\mathrm{s}}^2$
Again,
v=u+at
Final velocity, v=10 +(-2) x 10=-10 m/s
$$\begin{gathered} \mathrm{s}=\mathrm{ut}+\frac{1}{2}{\mathrm{at}}^2 \\ =10\times 10+\frac{1}{2}\times (-2)\times {10}^2 \\ =100-100=0 \\ \mathrm{Its}\mathrm{displacement}\mathrm{is}\mathrm{zero}. \end{gathered}$$