Why are rubber tires preferred over steel tires for vehicle wheels?

$A$ block of mass $m$ is pressed against a vertical wall by a horizontal force of magnitude $mg$. An upward force of magnitude $\frac{mg}{2}$ is also applied to the block. If the block is in equilibrium,the minimum coefficient of friction $\mu$ between the block and the wall is:

$A$ conveyor belt is moving at a constant speed of $2\, m s^{-1}$. $A$ box is gently dropped on it. The coefficient of friction between them is $\mu = 0.5$. The distance that the box will move relative to the belt before coming to rest on it,taking $g = 10\, m s^{-2}$,is ........... $m$.

$A$ body of mass $40\,kg$ resting on a rough horizontal surface is subjected to a force $P$ which is just enough to start the motion of the body. If $\mu_{s} = 0.5$,$\mu_{k} = 0.4$,$g = 10\,m/s^2$,and the force $P$ is continuously applied on the body,then the acceleration of the body is $.........\,m/s^2$.

Determine the maximum acceleration in $m/s^2$ of the train in which a box lying on its floor will remain stationary,given that the coefficient of static friction between the box and the train's floor is $0.15$.

$A$ particle of mass '$m$' at rest on a rough horizontal surface with a coefficient of friction '$\mu$' is given a velocity '$u$'. The average power imparted by friction before it stops is: