# Q & A: What is density?

Q:
What is density?
- Anonymous
A:
Density is how much stuff there is in some amount of space. It's typically measured as how much mass (which is a bit like how much it weighs) there is in so much space. (For example, scientists often measure it as how many grams per cubic centimeter.)

Let's say that we had two balls, a basketball and a bowling ball, and both are the same size. Since the bowling ball is heavier than the basketball, you know that it has to be more dense, since they both take up the same amount of space overall.

Another example to think of is if you've ever baked a cake and had to sift the flour. The reason for sifting the flour is to make it less dense, so the cake won't be as heavy. Before you sift it, it's very dense, because the flour is all packed together. Afterwards, it's very loose and takes up more space. So a cup of sifted flour weighs less than a cup of unsifted flour since it's denser.

Hope this helps!

-Tamara

(published on 10/22/2007)

## Follow-Up #1: measuring density

Q:
how you would determine the density of a piece of cork, gien a measuring cylinder, water and an electronic balance
- haha (age 13)
singapore
A:
It's easy. Weigh the cork to get its mass. Measure the volume of the water in the cylinder. Push the cork under water using something thin that won't take up much space itself. Measure what the new volume of the water + cork reads. Subtract to get the cork volume. Divide the cork mass by the cork volume and you have its density.

Mike W.

Lee H

(published on 10/22/2007)