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 upthrust on the block.
When the lift is accelerated upwards, `g_(eff)` becomes g+a instead of g.
Here, " " `F'=F((g+a)/(g))`
From Newton's second law,
F'-T-mg=ma