Determining Density Weight and Mass Weight and mass

Determining Density

Weight and Mass Weight and mass are not the same Weight: is a measure fo the force of gravity on an object Gravity is measured in newtons (N) A force of 1 N is about the amount of force exerted by an apple in your hand. So the weight of the apple is 1 N. Mass: measures the aount of matter or nuber of particles that are in the object

Is there a Relationship between Density and Mass? • if you were to go to the moon, you would find that the force of gravity is 1/6 of that on Earth, but the mass of an object on the moon is the same as on earth • the same volume of gold on Earth will have the same mass as the gold on the moon • the gold will weigh less on the moon than on Earth

How are Density and Mass related? • Density is the mass per unit of volume, which can be measured in m. L or cm 3 • so, Volume is important to know when determining the density of an object

Volume is a measurement of the amount of space occupied by the substance. How can we measure volume?

Measuring Volume 1. Liquids can be measured using a measuring cup or a graduated cylinder. 2. Gases can be determined by measuring the volume of the container it is in.

Measuring Volume 3. Irregular solids can be determined by immersing them into a beaker of water and measuring the volume of the displaced fluid. Displacement is the amount of space that an object takes up when placed in a fluid.

Measuring Volume 4. Regular solids can be determined by measuring the length, width, and height: V=l×w×h = 4 m x 3 m x 2 m = 24 m 3

How to Calculate Density (D) = Mass (m) or simply, D= m Volume V V= m and m = V x D D

Sample Problem Find the density of a 10 g mass of a substance that has a volume of 2. 0 cm 3. D=m V D= 10 g 2. 0 cm 3 = 5 g/cm 3

Sample Problem You want to put 10. 0 g of salt into a container. If the density of salt is 2. 16 g /cm 3 , what is the volume of the container if the salt completely fills it? V= m D V= 10. 0 g 2. 16 g/cm 3 V= 4. 6 g/cm 3

Sample Problem What is the mass of 1500 m. L of helium, if the density of helium is 0. 0002 g/m. L? m= D x V m= 0. 3 g m= 0. 0002 g/m. L x 1500 m. L

Assignment • Go over the sample problems provided • Complete the practice problems provided • Each of these documents are posted on the class website as well