A rope of negligible mass passes over a pulley of negligible mass attached to the ceiling, as shown in figure. One end of the rope is held by Student A of mass `70 kg`, who is at rest on the floor. The opposite end of the rope is held by Student `B` of mass `60 kg`, who is suspended at rest above the floor. The minimum acceleration `a_(0)` with which the Student `B` should climb up the rope to lift the Student A upward off the floor. `(g=10m//s^(2))`

Options

A. `(1)/(3)(m)/(s^2)`
B. `(2)/(3)(m)/(s^2)`
C. `(4)/(3)(m)/(s^2)`
D. `(5)/(3)(m)/(s^2)`

Answer

D

Explanation

For student A to just lift of the floor tension T in string must be greater than or equal to 700 N.
The F.B.D. Of student B is Applying Newton's second law
`T-mg=maimplies700-600=6a`
or `a=(5)/(3)(m)/(s^2)`