Question

A metal coin of thickness 'd' and density 'ρ' is floating on water of surface tension 'T'. The radius of the coin is ______.

g = acceleration due to gravity

Options

• `(4T)/(3rhogd)`

• `(3T)/(4rhogd)`

• `(2T)/(rhogd)`

• `T/(rhogd)`

Answer 1

A metal coin of thickness 'd' and density 'ρ' is floating on water of surface tension 'T'. The radius of the coin is `underline((2T)/(rhogd))`.

Explanation:

Let the radius of the coin be r

∴ m = πr² d ρ

Downward weight mg = πr² dρg

Upward force due to tension = 2πrT

∴ πr² dρg = 2πrT

`r=(2T)/(drhog)`