$A$ wooden block,initially at rest on the ground,is pushed by a force which increases linearly with time $t$. Which of the following curves best describes the acceleration of the block with time?

$A$ cricket ball of mass $50 \ g$ having velocity $50 \ cm \ s^{-1}$ is stopped in $0.5 \ s$. The force applied to stop the ball is (in $N$)

An object of mass $2 \, kg$ at rest at the origin starts moving under the action of a force $\vec{F} = (3t^2 \hat{i} + 4 \hat{j}) \, N$. The velocity of the object at $t = 2 \, s$ will be ............. $m/s$.

At any instant,the velocity of a particle of mass $500 \, g$ is $(2t \hat{i} + 3t^2 \hat{j}) \, ms^{-1}$. If the force acting on the particle at $t = 1 \, s$ is $(\hat{i} + x \hat{j}) \, N$,then the value of $x$ will be:

The magnitude of the external force acting on moving bodies can be known directly by

$A$ body,under the action of a force $\vec F = 6\hat i - 8\hat j + 10\hat k$,acquires an acceleration of $1\, m/s^2$. The mass of this body must be