$A$ rope of mass $5 \,kg$ is moving vertically in a vertical position with an upward force of $100 \,N$ acting at the upper end and a downward force of $70 \,N$ acting at the lower end. The tension at the midpoint of the rope is ......... $N$.

$A$ monkey of mass $40 \, kg$ climbs on a rope which can stand a maximum tension of $600 \, N$. In which of the following cases will the rope break: the monkey
$(a)$ climbs up with an acceleration of $6 \, m \, s^{-2}$
$(b)$ climbs down with an acceleration of $4 \, m \, s^{-2}$
$(c)$ climbs up with a uniform speed of $5 \, m \, s^{-1}$
$(d)$ falls down the rope nearly freely under gravity? (Ignore the mass of the rope).

Two spheres $P$ and $Q$,each of mass $200 \text{ g}$,are attached to a string of length $1 \text{ m}$ as shown in the figure. The string and the spheres are then whirled in a horizontal circle about $O$ at a constant angular speed. The ratio of the tension in the string between $P$ and $Q$ to that between $P$ and $O$ is (where $P$ is at the mid-point of the line joining $O$ and $Q$).

Two blocks of masses $m$ and $2m$ kept on a frictionless horizontal surface are connected by a massless string. Two horizontal forces $F_1 = (4.2t) \text{ N}$ and $F_2 = (7.5t) \text{ N}$,where '$t$' is time in seconds,are acting on the system as shown in the figure. The time at which the tension in the string between the two blocks becomes $10.6 \text{ N}$ is $t$ seconds.

Two blocks,each having mass $M$,rest on frictionless surfaces as shown in the figure. If the pulleys are light and frictionless,and $M$ on the incline is allowed to move down,then the tension in the string will be

$A$ balloon of mass $M$ descends with an acceleration $a (< g)$. What mass needs to be removed from the balloon so that it starts ascending with acceleration $a$?