$A$ body of mass $1 \,kg$ is moving with a velocity $10 \,ms^{-1}$ on a horizontal rough surface having a coefficient of kinetic friction $0.4$. If the constant force is removed, the body comes to rest in a time (Acceleration due to gravity $g = 10 \,ms^{-2}$). (in $\,s$)

"When a man walks on a rough surface,the frictional force acts in the direction opposite to his motion." Is this statement correct? Give reasons.

$A$ small body of mass $500 \,g$ moves on a rough horizontal surface before finally stopping. The initial velocity of the body is $2 \,m/s$ and the coefficient of friction is $0.3$. Find the absolute value of the average power developed by the frictional force during the time of motion. (Take $g = 10 \,m/s^2$) (in $\,W$)

$A$ cylinder of mass $12 \,kg$ is sliding on a plane with an initial velocity $20 \,ms^{-1}$. If the coefficient of friction between the surface and the cylinder is $0.5$, what is the distance the cylinder travels before stopping (in $\,m$)?

$A$ body is moving along a horizontal surface with a velocity of $4 \,m/s$. If the coefficient of kinetic friction is $0.2$, the distance travelled by the body before coming to rest is $(g = 10 \,m/s^2)$. (in $\,m$)

$A$ vehicle of mass $M$ is moving with momentum $P$ on a rough horizontal road. The coefficient of friction between the tyres and the horizontal road is $\mu$. The stopping distance is ($g$ $=$ acceleration due to gravity).