This is a problem on mensuration ( VOLUMES AND SURFACE AREAS)

[agnibho]

Homework Statement

A right circular cone of diameter r cm and height 12 cm rests on the base of right circular cylinder of radius r cm. their bases are in the same plane and the cylinder is filled with water up to a height of 12 cm. If the cone is then removed, find the height to which water level will fall

Homework Equations

The Attempt at a Solution

Radius of base of cone = r/2 cm Radius of the cylinder = r cm
Height of conical portion = 12 cm
or, Height of water in cylinder before cone taken out = 12 cm
Therefore, volume of water left in the cylinder when cone is taken out = πr²(12)- 1/3π(r/2)²*12 = πr²*11

Therefore, height of water left in cylinder = 11 cm

 

[HallsofIvy]

Looks good to me!

(It would be better to show that calculation in more detail- I had to think for a minute to see how you got "11"!)

 

[agnibho]

Thanks for the confirmation.

 

[Phrak]

Assume, though not clearly unstated that, the axes of cone and cylinder are aligned with the gravitational field vector and the cone is on top, or answers will vary.