The tension in a string holding a solid block below the surface of a liquid (of density greater than that of solid) as shown in figure is `T_(0)` when the system is at rest. What will be the tension in the string if the system has an upward acceleration a?
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Explanation

Let `m` be the mass of block. Initially for the equilibrium of block,
`F = T_(0) + mg`

Here, `F` is the upthurst on the block

Where the lift is accleerated upwards, `g_(eff)` becomes `g + a` instead of `g`. Hence,
`F' = F((g + a)/(g))`
From Newton's second law,
`F' - T - mg = ma`
Solving Eqs. `(i), (ii)` and `(iii)`, we get
`T = T_(0)(1 + (a)/(g))`