A constant force acting on a body of mass $3.0\; kg$ changes its speed from $2.0\; m s ^{-1}$ to $3.5\; m s ^{-1}$ in $25\; s$. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force?

At any instant the velocity of a particle of mass $500\,g$ is $\left(2 t \hat{ i }+3 t ^2 \hat{ j }\right)\,ms ^{-1}$. 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 graph below shows the variation of a force $F$ with time $t$ on a body which is moving in a straight line. Dependence of force on time is $F \propto t^{n}$. Initially body is at rest. If the speed of the object is $2 \,m / s$ at $3 \,s$, then the speed at $4 \,s$ will be approximately (in $m / s$ )

A body of mass $2 \,kg$ is sliding with a constant velocity of $4 \,m / s$ on a frictionless horizontal table. The force required to keep the body moving with the same velocity is ……….$N$