Pennies weight vs. Aerogel ?

[BSG CORP]

To weigh as much as a penny, how big would a ball of Aerogel have to be? It would have a diameter of about ...

 

35% - a) 15.75 cm

46% - b) 11.5 cm

12% - c) 6.25 cm

8% - d) 3 cm

 

Answer is: b) 11.5 cm

 

The latest aerogel weighs 1.9 milligrams per cubic centimetre, just .7 milligrams more than the same volume of air. Yet it's strong enough to support thousands of times it's own weight. It also withstands extreme temperatures, and as an insulator, aerogel is about 40% more efficient than fiberglass.

 

To get the answer you had to know that a penny weighs 2.35 grams. If you divide the weight of the penny by the weight of one cubic centimetre of aerogel, you get the total volume of aerogel.

 

Now you need to calculate the volume of the balls, to figure out which ball's volume is closest to the volume of aerogel.

 

The formula for calculating the volume of a sphere is: Volume = 4/3 x pi x radius cubed

 

pi=3.14

 

The radius is half of the diameter.

 

Now you can try plugging various ball radii into the formula to figure out which ball is the closest to the volume of the aerogel.