Measuring the density of a
solid object involves making two different
measurements then dividing one of them into the
other. First measure mass. That's the easy one. It
just requires an accurate balance that measures in
grams. Next, measure the volume of
the object in cubic centimeters. This measurement
is more complicated. First there are two different
ways to measure volume. If the object is a regular
solid (prism, cylinder, sphere, cone) you can
measure its dimensions then calculate its
volume. Sphere 4/3pr^{3} Cube edge^{3} Rectangular
Prism L x W x
H Cone 1/3pr^{2}h Pyramid area of the base *
height * 1/3 If the object is small, measure its volume by placing it in a partially filled graduated cylinder and noting the rise in water. For example: if a graduated cylinder contains 50 mL of water before you add the object, and 73 mL after, the object has a volume of 23 mL. Since one milliliter is equal to one cubic centimeter, the volume of this object can also be expressed as 23 cm^{3} . Reading a Graduated Cylinder If the object is too large to fit into a graduated cylinder what do you do? Displacement still works but you need a large container with a spout. Fill the container to a level above its spout. Place it on a level surface and allow the excess water to run out. Slowly lower the object into the water and collect all of the water that overflows. (If the object floats, you push it just below the surface of the water and hold it there until the flow of water stops.) Overflow Can Measure the volume of water that overflowed by pouring it into a graduated cylinder. Use the graduated cylinder as many times as it takes to measure all of the displaced water. Copyright © 2003-2013 Event-Based Science Institute |