1. ## Sphere

An ornamental spherical ball made of bronze has an outer diameter of 1.2m cm and a uniform thickness of 13cm. If bronze weighs 8.5 grams / cm^3, find the weight of the ball.

2. Originally Posted by reiward
An ornamental spherical ball made of bronze has an outer diameter of 1.2m cm and a uniform thickness of 13cm. If bronze weighs 8.5 grams / cm^3, find the weight of the ball.
1. Calculate the volume of the bronze which is the difference between the outer sphere and the inner sphere.
Convert all measures into cm. If $r_o$ denote the outer radius and $r_i$ the radius of the inner sphere then the volume of the bronze is:

$V_{bronze}=\frac43 \cdot \pi \left(r_o^3-r_i^3 \right)$

2. Since $density = \frac{mass}{volume}~\implies~mass=density \cdot volume$

3. Use the result from 1. to calculate the mass of the bronze.

4. If you are actually asked to find the weight of the bronze you have to multiply the result from 3. by $0.00981\ \frac Ng$

Spoiler:
I've got a mass of 3,994 kg that means nearly 4 tons