$A$ body of mass $5 \ kg$ is moving in a straight line. The relation between its displacement and time is $x = (t^3 - 2t - 10) \ m$. What is the force acting on it at the end of $5 \ s$ (in $N$)?

$A$ particle of mass $m$ is at rest at the origin at time $t = 0$. It is subjected to a force $F(t) = F_0e^{-bt}$ in the $x$ direction. Its speed $v(t)$ is depicted by which of the following curves?

$A$ body of mass $2\, kg$ travels according to the law $x = at + bt^2 + ct^3$,where $a = 3\, m/s$,$b = 4\, m/s^2$,and $c = 5\, m/s^3$. The force acting on the body at $t = 2\, s$ is ......... $N$.

$A$ body of mass $0.05 \ kg$ is observed to fall with an acceleration of $9.5 \ ms^{-2}$. The opposing force of air on the body is $(g = 9.8 \ ms^{-2})$.

$A$ force separately produces accelerations of $18 \ m/s^2$,$9 \ m/s^2$,and $6 \ m/s^2$ in three bodies of masses $P$,$Q$,and $R$ respectively. If the same force is applied on a body of mass $P+Q+R$,then the acceleration of that body is: (in $m/s^2$)

$A$ $10 \; N$ force is applied on a body,producing an acceleration of $1 \; m/s^2$ in it. The mass of the body is ...... $kg$.