A force of 20 N acts on a body of mass 5kg at rest. What is the acceleration of the body ? What is its velocity after 5 seconds if the same force acts? After 5 seconds if the force ceases to act how will the body move?

$$\begin{gathered} \mathrm{F} = \mathrm{ma} \\ \mathrm{where} \mathrm{F} \mathrm{is} \mathrm{given} \mathrm{as} 20 \mathrm{N}, \mathrm{mass} \mathrm{m} = 5\mathrm{kg} \\ \Rightarrow \mathrm{acceleration} \mathrm{a} =\frac{ 20\mathrm{N}}{5\mathrm{kg}} = 4 \raisebox{1ex}{$\mathrm{m}$}\!\left/ \!\raisebox{-1ex}{${\mathrm{s}}^2$}\right. \end{gathered}$$

Since, v= u + at and initial velocity u = 0

velocity after 5 seconds is v = (4)x(5) = 20m/s

Once the force ceases to act the acceleration becomes 0 and the body will keep moving uniform velocity.