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Density Density Density= Mass Volume D= m V Mass • Mass: Amount of matter in a substance. • Units: Grams (g) Kilograms (kg) • Don’t confuse with weight. Weight: the force with which the earth pulls on the substance (Gravity). Volume • Volume is the amount of space an object takes up • Units for volume: ml Milliliters L liters centimeters cubed cm3 Volume of a regular solid Length (L) x Width (W) xHeight (H)=units3 Calculating volume of irregular objects • Use a graduated cylinder For water displacement • Add water to a predetermined level record. • Gently drop in the irregularly shaped object. • Read the graduated cylinder – record. • Subtract the first water level from the second – this is the volume Question Which weighs more? 50 kilograms of iron Or 50 kilograms of feathers Question Which has a greater density? iron Or feathers Common Units of Density Density= Mass (g) Volume (ml or cm3) g/mL = g/cm3 1 mL=1 cm3 kg/m3 Densities of Common Substances Density of Water • At 4oC water has its maximum density of 1g/cm3 • -Ice is less dense than water so it floats on the top of water Density of Water and ICE Density is a constant • Density is an intrinsic physical property. -Never Changes for a substance -Does not depend on amount of matter (mass) you have Will It float • If an object is less dense than the fluid it is in it will sink • If object is equally dense it will Suspend • If object is more dense it will sink Note (fluid/Liquid does not have to be water) Calculating Density Using the triangle 1.Cover up what you are trying to find 2. If the other letters are next to each other you multiply them 3. If one is above the other than you divide the top by the bottom