$A$ body is imparted motion from rest to move in a straight line. If it is then obstructed by an opposite force,then:

Place a uniform meter scale horizontally on your extended index fingers with the left one at $0.00 \ cm$ and the right one at $90.00 \ cm$. When you attempt to move both fingers slowly towards the center,initially only the left finger slips with respect to the scale and the right finger does not. After some distance,the left finger stops and the right one starts slipping. Then the right finger stops at a distance $x_R$ from the center $(50.00 \ cm)$ of the scale and the left one starts slipping again. This happens because of the difference in the frictional forces on the two fingers. If the coefficients of static and dynamic friction between the fingers and the scale are $0.40$ and $0.32$,respectively,the value of $x_R$ (in $cm$) is:

Two blocks of equal masses are connected with a massless spring of spring constant $k = 2500 \,N/m$ and natural length $10 \,cm$,resting on a frictionless horizontal plane. If a constant horizontal force $F = 10 \,N$ is applied as shown in the figure,find the maximum distance between the blocks. (in $cm$)

$A$ force acts for $20\,s$ on a body of mass $20\,kg$,starting from rest,after which the force ceases and the body travels $50\,m$ in the next $10\,s$. The value of the force is $..........\,N$.

Three blocks $A, B$ and $C,$ of masses $4 \, kg, 2 \, kg$ and $1 \, kg$ respectively,are in contact on a frictionless surface,as shown. If a force of $14 \, N$ is applied on the $4 \, kg$ block,then the contact force between $A$ and $B$ is .......... $N$.

Two balls of masses $m_1$ and $m_2$ are separated from each other by a powder charge placed between them. The whole system is at rest on the ground. Suddenly,the powder charge explodes and the masses are pushed apart. The mass $m_1$ travels a distance $s_1$ and stops. If the coefficients of friction between the balls and the ground are the same,the mass $m_2$ stops after travelling the distance: