Question

Figure shows a heavy block kept on a frictionless surface and being pulled by two ropes of equal mass $m .$ At $t=0,$ the force on the left rope is withdrawn but the force on the right end continues to act. Let $F_{1}$ and $F_{2}$ be the magnitudes of the forces by the right rope and the left rope on the block respectively. Then

• A. $F_{1}=F_{2}=F$ for $t<0$
• B. $F_{1}=F_{2}^{2}=F+m g$ for $t<0$
• C. $F_{1}=F, F_{2}=F$ for $t>0$
• D. $F_{1}0$

Answer 1

Answer: (A)

(a) is valid due to symmetry and since acceleration is 0 initially $F_{1}=F$ and similarly $F_{2}=F$

(b) is out, since $m g$ is a vertical force and has got nothing to do with horizontal forces.
(c) and $(d) $ are ruled out, as $F_{2} \neq F$ as $F$ acts on the whole system and $F_{2}$ acts on $m$ only for $t>0$