Imagine a situation in which the horizontal surface of block $M_0$ is smooth and its vertical surface is rough with a coefficient of friction $\mu$. In the above problem,choose the correct value$(s)$ of $F$ for which the blocks $M$ and $m$ remain stationary with respect to $M_0$.

In the given figure, the blocks $A$, $B$, and $C$ weigh $4 \ kg$, $6 \ kg$, and $8 \ kg$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is . . . . . . $N$. (Use $g = 10 \ m/s^2$)

Consider two blocks of mass $m_1 = 5 \, kg$ and $m_2 = 10 \, kg$ placed on a horizontal surface. The coefficient of static friction between the blocks and the surface is $\mu = 0.2$. $A$ horizontal force $F$ is applied to the $10 \, kg$ block. What is the maximum force $F$ (in $N$) that can be applied such that neither block moves? (Take $g = 10 \, m/s^2$)

$A$ helicopter of mass $2000 \,kg$ rises with a vertical acceleration of $15 \,m s^{-2}$. The total mass of the crew and passengers is $500 \,kg$. Calculate the magnitude and direction of the following (take $g = 10 \,m s^{-2}$):
$(a)$ Force on the floor of the helicopter by the crew and passengers.
$(b)$ Action of the rotor of the helicopter on the surrounding air.
$(c)$ Force on the helicopter due to the surrounding air.

$Assertion$: On a rainy day,it is difficult to drive a car or bus at high speed.
$Reason$: The value of the coefficient of friction is lowered due to the wetting of the surface.

$A$ truck of mass $M$ is at rest on a frictionless road when a monkey of mass $m$ starts moving on the truck in the forward direction. If the truck recoils with a speed $v$ backward on the road,with what velocity is the monkey moving with respect to the truck?