Under the action of a force, a $1 \mathrm{kg}$ body moves, such that its position $x$ as a function of time $t$ is given by $x=\frac{t^3}{2},$ where $x$ is in meter and $t$ is in second. The work done by the force in first $3$ second is

A particle of mass $0.1 \mathrm{kg}$ is subjected to a force which varies with distance as shown in figure. If it starts its journey from rest at $x=0 \mathrm{m},$ its velocity at $x=12 \mathrm{m}$ is

A body of mass $2 \mathrm{kg}$ starts with an initial velocity $5 {\mathrm{ms}}^{-1}.$ If the body is acted upon by a time dependent force $\left(F\right)$ as shown in figure, then work done on the body in $20 \mathrm{s}$ is