The inner radius of a hollow iron sphere is 9cm. If iron is 1cm thick, find the volume of iron used to make the ball.
1134.59 cm3
Thickness of the iron = 1cm
Inner radius = 9cm
Therefore, inner volume of sphere = 43 π (rinner)3
=43 × π × (9)3
=3052.08cm3
Outer radius = 10cm
Outer volume = 43 ×π × (router)3
=43 π (10)3
=4186.67cm3
Then, iron used = Outer volume - Inner volume
=1134.59 cm3