Density of Irregularly Shaped Objects Created by Kesler Science – More 5E lessons at KeslerScience.com Presented by Kesler Science

Essential Questions: How do you calculate the density of irregularly shaped objects? How can calculating density help determine the identity of an unknown substance?

Density – Irregularly Shaped Objects Archimedes 287BC -212BC Greatest mathematician and scientist of antiquity Discovered method to help determine the volume of irregularly shaped objects © KeslerScience.com

Eureka !! The Archimedes’ Principle Density – Irregularly Shaped Objects The Archimedes’ Principle Eureka !! Noticed when he stepped into his bath the water level rose. Understood that the volume of water displaced must be equal to the volume of the part of his body he submerged. Eureka is what Archimedes reportedly shouted when he discovered how to calculate volume of an an irregular shaped object © KeslerScience.com

Check for Understanding Do you remember… How to make readings of liquid levels in a graduate? Always read from the lowest part of the meniscus. © KeslerScience.com

Volume The amount of space an object takes up. Density – Irregularly Shaped Objects What is the volume of liquid in the graduate? Volume The amount of space an object takes up. Measured with a graduated cylinder. Units - liter, milliliters © KeslerScience.com

Density – Irregularly Shaped Objects Displacement The difference between the initial volume (110ml) and the volume after an object is submerged (175 ml). © KeslerScience.com

Density – Irregularly Shaped Objects V1 V2 How do you find the volume of an irregularly shaped object? V = V2 – V1 Initial volume – V1 = 20 ml Final volume – V2 = 23 ml Volume of object V = 3 ml © KeslerScience.com

Quick Action – Density - Irregular Objects Practice What is the initial volume? What is the volume after the ball was added? Subtract the 1st volume from the 2nd volume. Answer – 4ml © KeslerScience.com

The amount of matter in an object. Density – Irregularly Shaped Objects Mass The amount of matter in an object. Measured with a triple beam balance or a scale. Units – grams, milligrams © KeslerScience.com

Density – Irregularly Shaped Objects Measure of how compact a substance is in a given volume. The more molecules in a given volume the greater the density. The fewer molecules in a given volume the less the density. Least dense Most dense © KeslerScience.com

Density – Irregularly Shaped Objects Why do things float? Objects with a density greater than 1 will sink in water. (Closely spaced) Objects with a density less than 1 will float in water. (Less closely spaced) Which object will float? 7.2 g/mi Penny 1 g/mi Water .75 g/ml Wood beads © KeslerScience.com

How do you calculate density? Density – Irregularly Shaped Objects MASS VOLUME How do you calculate density? Density = Mass Volume Units – g/ml or g/cm3 © KeslerScience.com

Density – Irregularly Shaped Objects What is the volume of the ball? What is the density of the ball if it has a mass of 20 grams? 20 g ?ml Answer 20g/4ml = 5 g/ml © KeslerScience.com

Quick Action - Density – Irregular Objects Practice You found a large object near a construction site and want to determine what it is made of. You measured its mass as 8.1 grams and its volume at 3 cm3. What is its density? What substance is your unknown object made of? Common Substances Density (g/cm3) Air 0.0013 Feather 0.0025 Pine 0.5 Ice 0.92 Water 1.00 Bricks 1.84 Aluminum 2.70 Steel 7.80 Silver 10.50 Gold 19.30 answer © KeslerScience.com

Density – Irregularly Shaped Objects What careers may use density? Geologist - to identify minerals. Chemical Engineers - to identify liquids and other substances. Ship builders -to determine if ship will float. © KeslerScience.com

Check for Understanding MASS VOLUME Can you… Calculate the density of an irregularly shaped object? Identify an unknown object by calculating its density? © KeslerScience.com