Which one of the following statements is correct?

$A$ 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 $.........\,m/s^2$.

$A$ 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:

$A$ block of mass $1.5 \ kg$ kept on a rough horizontal surface is given a horizontal velocity of $10 \ ms^{-1}$. If the block comes to rest after travelling a distance of $12.5 \ m$,the coefficient of kinetic friction between the surface and the block is (Acceleration due to gravity $= 10 \ ms^{-2}$)

Calculate the stopping distance of a vehicle of mass $M$ moving with velocity $v$ on a straight road. (Where $\mu$ is the coefficient of friction between the tires and the road.)

$A$ body of mass $10 \,kg$ is kept on a horizontal surface. The coefficient of kinetic friction between the body and the surface is $0.5$. $A$ horizontal force of $60 \,N$ is applied on the body. The resulting acceleration of the body is about