A ball of mass $1 \mathrm{kg}$ strikes a rigid wall with speed $2 \mathrm{m} {\mathrm{s}}^{-1}$ and gets reflected without any loss of speed as shown. The magnitude of impulse is

A block of mass $M=2 \mathrm{kg}$ is resting on a rough horizontal surface for which the coefficient of friction is $0.2.$ When a force $F=20 N$ is applied, the acceleration of the block will be $\left(g=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$

A body of mass $1 \mathrm{kg}$ is acted on by a force $\left(F\right)$ which varies with time $\left(t\right)$ as shown in the graph below. The momentum acquired by the body in $2 \mathrm{s}$ if it starts from rest is