A cylindrical jar of radius 6 cm contains oil. Iron spheres each of radius 1.5 cm are immersed in the oil. How many spheres are necessary to raise the level of the oil by two centimetres ?
Given radius of cylinder =6cm,
radius of each sphere =1.5cm
raise in the level of oil=2cm
Volume of the raised oil in the cylinder = πr2h=π×62×2=72π cm3
Volume of 1 sphere
Let the number of sphere which when immersed in the oil raise the level by 2cm be n.
Volume of n spheres = =n×9π2cm3 =Volume of the raised oil
Hence the required number of spheres=16