You have two solid steel spheres; sphere 2 has twice the radius of sphere 1. what is the ratio of the moments of inertia, i2 : i1?

Explanation:

The momentum of inertia of the solid sphere is :

m is the mass of solid sphere

r is the radius of sphere

Since,

........................(1)

Let r' is the radius of second sphere such that, r' = 2r. New moment of inertia is given by :

Similarly,

.

........................(2)

Dividing equation (1) and (2) as :

So, the ratio of their moments off inertia is 32:1

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form