$A$ boat of mass $700 \,kg$ is travelling at a speed of $24 \,ms^{-1}$ when its engine is shut off. The magnitude of frictional force $f$ between the boat and water is given by $f = 35v$, where $v$ is the speed in $ms^{-1}$ and $f$ is in newton. Find the time taken for the speed of the boat to become $6 \,ms^{-1}$. (in $\,s$)

$A$ car having a mass of $1000\, kg$ is moving at a speed of $30\, m/s$. Brakes are applied to bring the car to rest. If the frictional force between the tyres and the road surface is $5000\, N$,the car will come to rest in ........ $s$.

$A$ $300 \ kg$ crate is dropped vertically onto a conveyor belt that is moving at $1.20 \ m/s$. $A$ motor maintains the belt's constant speed. The belt initially slides under the crate,with a coefficient of friction of $0.400$. After a short time,the crate is moving at the speed of the belt. During the period in which the crate is being accelerated,find the work done by the motor which drives the belt.

$A$ block of mass $10\, kg$ moving at $10\, m/s$ is released to slide on a rough surface having a coefficient of friction $0.2$. It will stop after travelling a distance of ........ $m$.

$A$ body of mass $m$ moves with a velocity $v$ on a surface whose friction coefficient is $\mu$. If the body covers a distance $s$ before coming to rest,what is the initial velocity $v$?

When we rub our palms,they get heated,but only up to a maximum temperature because: