$A$ motor car moving with velocity $7 \ m/s$ stops in $10 \ m$ distance when brakes are applied. What is the relation between the resistance force $(R)$ and the weight $(W)$ of the car? (Take value of $g = 9.8 \ m/s^2$)

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

$A$ uniform wooden stick of mass $1.6 \,kg$ and length $l$ rests in an inclined manner on a smooth, vertical wall of height $h$ < $l$ such that a small portion of the stick extends beyond the wall. The reaction force of the wall on the stick is perpendicular to the stick. The stick makes an angle of $30^{\circ}$ with the wall and the bottom of the stick is on a rough floor. The reaction of the wall on the stick is equal in magnitude to the reaction of the floor on the stick. Find the ratio $h/l$ and the frictional force $f$ at the bottom of the stick. $(g=10 \,m \,s^{-2})$

If $M_2 = 2M_1$ and $\theta = 30^\circ$,the acceleration of $M_2$ is $a$. If the positions of the blocks are interchanged,what will be the acceleration of $M_2$?

$A$ parachutist with a total mass of $75 \,kg$ drops vertically onto sandy ground with a speed of $2 \,m/s$ and comes to a halt over a distance of $0.25 \,m$. The average force exerted by the ground on her is close to ............ $N$.

In the figure,a ball of mass $m$ is tied with two strings of equal length as shown. If the rod is rotated with angular velocity $\omega$,then