It is difficult to move a cycle with brakes on because

$A$ 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 ...........

$A$ block of mass $5 \,kg$ moving on a rough surface with a velocity of $4 \,ms^{-1}$ is stopped by friction in $2 \,s$. The coefficient of friction between the contact surfaces is (Acceleration due to gravity $g = 10 \,ms^{-2}$)

$A$ stone weighing $1$ kg and sliding on ice with a velocity of $2$ m/s is stopped by friction in $10$ sec. The force of friction (assuming it to be constant) will be ......... $N$.

$A$ bag is gently dropped on a conveyor belt moving at a speed of $2\,m/s$. The coefficient of friction between the conveyor belt and the bag is $0.4$. Initially,the bag slips on the belt before it stops slipping due to friction. The distance travelled by the bag on the belt during the slipping motion is $.....m$. [Take $g=10\,m/s^{-2}$]

$A$ $60 \, kg$ mass is dragged on a horizontal surface by a rope for a distance of $2 \, m$. If the coefficient of friction is $\mu = 0.5$,the angle of the rope with the surface is $60^\circ$,and $g = 9.8 \, m/s^2$,then the work done against friction is ........ $J$.