Question

A cone with diameter r centimetres and height of 12 centimetre rest on a cylinder having radius of r centimetre the cone and cylinder are both on same plane water is filled in the cylinder up to the height of 12 centimetres if the cone is removed from what will be the height that will the water will be falling?

Answer 1

Volume of cone $=\frac{1}{3}\pi (r{)}^2\times 12=\pi r^{2}cc$
Actual amount of water = volume of cylinder - Volume of cone up to 12
$=12\pi r^2-\pi r^2=11\pi r^2$
Hence when coneis remained, the entire quality of water occupies space is cylinder As the entire quality of water $=11\pi r^2$, the height to which cylinder is filled in 11 cm.
So, water level will fall from 12 cm to 11 cm i.e.1 cm fall.