Question

Practice Problems 5
1. An aluminium cube of side 5 cm and R.D. 2.7 is suspended by a thread in alcohol of relative
density 0.80. Find the tension in thread.​

Answer 1

Given,

• An aluminium cube of side 5 cm.
• R.D. 2.7 is suspended A thread in Alcohol
• The thread in alcohol of relative density 0.80.

To Find,

• The tension in thread.

Solution,

Volume of Cube of Aluminium

= a^3 •••[Side = 5cm]

= 5cm^3

= 125cm^3

• Relatively Density of Aluminium = 2.7 •••(Given)
• Relatively Density of Alcohol = 0.8 •••(Given)
• Relatively Density of Water = 1

Relatively Density of Aluminium = p = 2.7

Mass of Aluminium = V × p

= 125 × 2.7

= 337.5 gf

So,

Weight of Aluminium = 337.5 gf

Volume of Displacement of Alcohol

= Volume of Cube of Aluminium

= 125{cm}^{3}

Upthrust of Alcohol ;

$V \: \times \: Density \: of\: (alcohol)$

Relatively Density of Alcohol ;

$\frac{ Density \: of\: (alcohol) }{ Density \: of \: water}$

$0.80 = \frac{ \: Density \: of\: (alcohol) }{1}$

So,

Density of Alcohol = 0.80

Upthrust of Alcohol

$V \: \times \: Density \: of\: (alcohol)$

= 125 × 0.80

= 100 gf

Required Answer,

So,

The tension in tread

= Weight of Aluminium - Upthrust of Alcohol

= 337.5 gf - 100 gf

= 237.5 gf

Answer 2

Hope it's helpful to you