Question

The ball of a float has a diameter of 4-in, and the thickness of the metal is 0.05 in. How much does it weigh if it is made of copper? (Copper weighs 556 lb. per cu. ft.)

Answer 1

Volume of the entire ball$= \frac{4}{3} \pi ^3$

Volume $=\frac{4}3*\frac{22}7*2^3$

Volume $=33.524 in^3$

The volume of the hollow area of the ball $=\frac{4}3 \pi^3$

V$=\frac{4}3*\frac{22}7*[2-0.05]^3$

$V=31.0719 in^3$

Volume of copper $=33.524-31.072$

$V of \space copper =2.452in^3$

Density of Cu$=0.324 lb/in^3$

Mass of Cu$=Density \space of \space Cu*Volume \space of \space Cu$

Mass of Cu$=0.324*2.452$

Mass of Cu$=0.794 lb$

Weight of copper $=0.794 *2.204*10$

Weight of copper$=17.510kg$