$A$ car of mass $1250 \ kg$ is moving with a velocity of $30 \ m/s$. $A$ resistive force of $750 \ N$ acts on it. If the engine produces a power of $30 \ kW$,what is the acceleration of the car in $m/s^2$?

In which of the following graphs,the total change in momentum is zero?

Fill in the blanks:
$(a)$ The friction acting on both wheels of a moving bicycle is in the ..... direction.
$(b)$ Friction depends on the ........... and ........ of the contact surfaces.
$(c)$ The necessary condition for parking a vehicle on a banked,curved road is ...........
$(d)$ The time rate of change of momentum gives the physical quantity ...........

$A$ $10 \, kg$ ball attached to the end of a rigid massless rod of length $L = 1 \, m$ rotates at a constant speed in a horizontal circle of radius $r = 0.5 \, m$ and period $T = 1.57 \, s$ as shown in the figure. The force exerted by the rod on the ball is ........ $N$.

In a tug-of-war contest,two men pull on a horizontal rope from opposite sides. The winner will be the man who

$A$ block of mass $m$ is moving with a constant acceleration $a$ on a rough plane. If the coefficient of friction between the block and the ground is $\mu$,the power delivered by the external agent after a time $t$ from the beginning is equal to: