Question

A metal cube of edge 5 cm and density 90 g cm-³ is
suspended by a thread so as to be completely immersed
in a liquid of density 1.2 g cm-³. Find the tension in
thread. (Take g = 10 m s-2)
[Hint: Tension in thread = Apparent weight of the cube
in liquid]
Ans. 9.75 N​

Answer 1

according to my calculation,

Side of the cube =5 cm

So, its volume , V=a3=125 cm3

Mass of cube =V×d=125×9=1125 g

Weight =mg=1125×1000=1125000 dyne

Now, cube is immersed is liquid, 

∴ buoynat force =Vρg=125×1.2×1000=150000 dyne

So, Tension = apparent weight =(1125000−150000) dyne=975000 dyne=9.75 N