$A$ spring-block system is placed on a rough horizontal floor. The block is pulled towards the right to give the spring some elongation and then released. The block will have maximum velocity when:

$A$ block of mass $m=2 \ kg$ is initially at rest on a horizontal surface. $A$ horizontal force $F_1=(6 \ N) \hat{i}$ and a vertical force $F_2=(10 \ N) \hat{j}$ are then applied to the block. The coefficients of static friction and kinetic friction for the block and the surface are $0.4$ and $0.25$, respectively. The magnitude of the frictional force acting on the block is (assume $g=10 \ m/s^2$): (in $N$)

$A$ block of mass $5\, kg$ is kept on a rough horizontal floor. It is given a velocity $33\, m/s$ towards the right. $A$ force of $20\sqrt{2}\, N$ continuously acts on the block as shown in the figure. If the coefficient of friction between the block and the floor is $0.5$, the velocity of the block after $3\, seconds$ is ........ $m/s$ $(g = 10\, m/s^2)$.

$A$ block of mass $10 \, kg$ is placed on a rough horizontal surface having a coefficient of friction $\mu = 0.5$. If a horizontal force of $100 \, N$ is acting on it,then the acceleration of the block will be ....... $m/s^2$.

$A$ 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 $g = 10\,m/s^2$)

$A$ $60 \, kg$ 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 ........ $J$.