A constant retarding force of $50 \mathrm{N}$ is applied to a body of mass $20 \mathrm{k}\mathrm{g}$ moving initially with a speed of $15 \mathrm{m}{\mathrm{s}}^{–1}$. How long does the body take to stop?

A pebble of mass $0.05 \mathrm{kg}$ is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, during its upward motion. (Ignore air resistance and take $g=10 \mathrm{m} {\mathrm{s}}^{-2}$)

Figure shows the position-time graph of a particle of mass $4 \mathrm{k}\mathrm{g}$. What is the force on the particle for $t<0, t>4 \mathrm{s}, 0<t<4 \mathrm{s}$? And impulse at $t=0$ and $t=4 \mathrm{s}$? (Consider one-dimensional motion only).