$A$ block of mass $10 \ kg$ is moving on a rough surface with a velocity $v = 4 \ m/s$ to the left. An external force $F = 20 \ N$ is applied to the right as shown in the figure. The coefficient of kinetic friction is $\mu = 0.6$. The frictional force acting on the block is ...... $N$.

$A$ body of mass $10\,kg$ is moving with an initial speed of $20\,m/s$. The body stops after $5\,s$ due to friction between the body and the floor. The value of the coefficient of friction is (Take acceleration due to gravity $g = 10\,m/s^2$)

$A$ block of mass $10 \, kg$ moving with an acceleration of $2 \, m/s^2$ on a horizontal rough surface is shown in the figure. The value of the coefficient of kinetic friction is ...........

$A$ 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

$A$ body is pulled along a rough horizontal surface with a velocity $6\,m/s$. If the body comes to rest after travelling $9\,m$,then the coefficient of sliding friction is- (Take $g = 10\,m/s^2$)

$A$ block of mass $40 \,kg$ slides over a surface,when a mass of $4 \,kg$ is suspended through an inextensible massless string passing over a frictionless pulley as shown below. The coefficient of kinetic friction between the surface and the block is $0.02$. The acceleration of the block is ............ $m/s^2$. (Given $g = 10 \,m/s^2$.)