From the following graph,find the magnitude of the negative force in $N$.

$A$ particle of mass $2/3 \, kg$ with velocity $v = -15 \, m/s$ at $t = -2 \, s$ is acted upon by a force $F = k - \beta t^2$. Here,$k = 8 \, N$ and $\beta = 2 \, N/s^2$. The motion is one-dimensional. Then,the speed at which the particle acceleration is zero again,is ........... $m/s$.

$A$ body of mass $5 \; kg$ is acted upon by two perpendicular forces $8 \; N$ and $6 \; N$. Find the magnitude and direction of the acceleration of the body.

$A$ body of mass $2 \ kg$ moving with velocity of $\overrightarrow{v}_{in} = 3 \hat{i} + 4 \hat{j} \ ms^{-1}$ enters into a constant force field of $6 \ N$ directed along the positive $z$-axis. If the body remains in the field for a period of $\frac{5}{3} \ s$, then the velocity of the body when it emerges from the force field is:

$A$ spherical body of mass $2\,kg$ starting from rest acquires a kinetic energy of $10000\,J$ at the end of $5^{\text{th}}$ second. The force acting on the body is $.....N$.

$A$ body of mass $5 \ kg$ starts from the origin with an initial velocity $(30 \hat{i} + 40 \hat{j}) \ m/s$. If a constant force $-(\hat{i} + 5 \hat{j}) \ N$ acts on the body,then the time in which the $y$-component of its velocity becomes zero is (in $s$)