What is dynamics?

The linear momentum $p$ of a body of mass $5 \,kg$ varies with time $t$ as $p = 5t^2 + t + 5$. It follows that the body is moving with:

$A$ force $\vec{F_1}$ of magnitude $4 \ N$ acts on an object of mass $1 \ kg$ at the origin in a direction $30^{\circ}$ above the positive $x$-axis. $A$ second force $\vec{F_2}$ of magnitude $4 \ N$ acts on the same object in the direction of the positive $y$-axis. The magnitude of the acceleration of the object is nearly: (in $m \ s^{-2}$)

$A$ 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 $N$)?

$A$ force $(2 \hat{i} + \hat{j} - \hat{k}) \text{ N}$ acts on a body, which is initially at rest. At the end of $20 \text{ s}$, the velocity of the body is $(4 \hat{i} + 2 \hat{j} - 2 \hat{k}) \text{ ms}^{-1}$. The mass of the body is: (in $\text{ kg}$)

$A$ force of $5 \, N$ acts on a body of weight $9.8 \, N$. What is the acceleration produced in $m/s^2$?