Question

24. A ball floats in water with 1/3 of its volume above the surface of the water. The water has density pw. What is the density of the ball?

Answer 1

Let 'g' be the acceleration due to gravity. 'p' be the density of water. So, p = 1 g/cm³ .

'V' be the volume of the Rubber and 'q' be the density of the Rubber.

Volume of Rubber within water = V – (1/3)V = (2/3)V = Volume of water displaced by the Rubber

Weight of the water displaced = (2/3)V × p × g

Weight of the Rubber = V × q × g

Since,

Rubber is floating on the surface,

(2/3)V × p × g = V × q × g

=> q = (2/3)p

That is, the density of the Rubber is (2/3) g/cm³.

2/3=0.66666666667 g/cm³

then change into the kg/m³

2/3 = 666.667 kg/m³