An object of mass $1 \,kg$ moving on a horizontal surface with initial velocity $8 \,m/s$ comes to rest after $10 \,s$. If one wants to keep the object moving on the same surface with velocity $8 \,m/s$,the force required is ...... $N$.

$A$ $60 \, kg$ mass is dragged on a horizontal surface by a rope for a distance of $2 \, m$. If the coefficient of friction is $\mu = 0.5$,the angle of the rope with the surface is $60^\circ$,and $g = 9.8 \, m/s^2$,then the work done against friction is ........ $J$.

$A$ block of mass $m$ slides along a floor while a force of magnitude $F$ is applied to it at an angle $\theta$ as shown in the figure. The coefficient of kinetic friction is $\mu_{K}$. Then,the block's acceleration $a$ is given by: ($g$ is acceleration due to gravity)

$A$ horizontal force of $40\,N$ is applied to a $5\,kg$ block which is at rest on a horizontal surface. If the coefficient of kinetic friction is $0.4$,then the acceleration of the block is ........ $m/s^2$ $(g = 10\,m/s^2)$.

$A$ body of mass $10 \,kg$ is kept on a rough horizontal surface with a coefficient of friction of $0.3$. If a horizontal force of $50 \,N$ is applied to the body, then the acceleration of the body is (Acceleration due to gravity $= 10 \,ms^{-2}$) (in $\,ms^{-2}$)

The power required for an engine to maintain a constant speed of $50 \,m \,s^{-1}$ for a train of mass $3 \times 10^6 \,kg$ on rough rails is (The coefficient of kinetic friction between the rails and wheels of the train is $0.05$ and acceleration due to gravity $= 10 \,m \,s^{-2}$).