Floating & Sinking Notes p. 52 Floating & Sinking Notes

I. Buoyancy Ability to float Archimedes’ principle – buoyant force = weight of fluid displaced

A solid block of steel sinks when placed in water A solid block of steel sinks when placed in water. A steel ship with the same weight floats.

II. Density Mass per unit volume “How much stuff in a specific amount of space”

1. Examples: a) Mass = 50 g, Volume = 5 mL b) Mass = 100 g, Volume = 10 cm3

2. Comparing Densities Density of pure water = 1 g/mL If an object is MORE dense, it will _____ If an object is LESS dense, it will _____ If it has EQUAL density, __________ sink float suspends

Density - Floating and Sinking Changes in density cause a submarine to dive, rise, or float.

Comprehension Check

1) Which has the greater density? Coke Diet Coke They have the same density Not enough information

2) Assuming this is a tank of pure water… What is the density of Coke? < 1 g/mL > 1 g/mL = 1 g/mL Not enough information

3) Which block has the higher density? They’re the same Not enough information

4) Calculate the density: Mass = 10 g; Volume = 10 mL 1 g/mL 10 g/mL 100 g/mL Not enough information

5) Identify the unknown substance if Mass = 20 g; Volume = 20 mL Gold Air Water Methanol

6) What property determines whether an object floats or sinks? Weight Density Temperature Speed

References http://www.pbs.org/wgbh/nova/lasalle/buoybasics.html http://www.nyu.edu/pages/mathmol/textbook/density.html