$A$ block of mass $2 \,kg$ is being pushed against a wall by a force $F=90 \,N$ as shown in the figure. If the coefficient of friction is $0.25$, then the magnitude of acceleration of the block is (Take $g=10 \,ms^{-2}$, $\sin 37^{\circ}=\frac{3}{5}$). (in $\,ms^{-2}$)

$A$ horizontal force of $129.4 \, N$ is applied on a $10 \, kg$ block which rests on a horizontal surface. If the coefficient of friction is $0.3$,the acceleration should be ....... $m/s^2$.

Consider a car moving along a straight horizontal road with a speed of $72 \, km/h$. If the coefficient of kinetic friction between the tyres and the road is $0.5$,the shortest distance in which the car can be stopped is ........ $m$. $[g = 10 \, m/s^2]$

$A$ block of a certain mass is placed on a rough floor. The coefficients of static and kinetic friction between the block and the floor are $0.4$ and $0.25$ respectively. $A$ constant horizontal force $F = 20 \text{ N}$ acts on it so that the velocity of the block varies with time according to the following graph. The mass of the block is nearly (Take $g = 10 \text{ m/s}^2$): (in $\text{ kg}$)

Two blocks of masses $M_1$ and $M_2$ are connected with a string passing over a pulley as shown in the figure. The block $M_1$ lies on a horizontal surface. The coefficient of friction between the block $M_1$ and the horizontal surface is $\mu$. What additional mass $m$ should be placed on the block $M_1$ so that the system does not accelerate?

What is the angle between the instantaneous velocity and the friction force of an object moving on a rough surface (in $^{\circ}$)?