Presentation on theme: "Floating and Sinking. Density is a measure of how closely packed the atoms in a substance are Density is a physical property All matter has measurable."— Presentation transcript:
The density of a substance is its mass per unit of volume. For example, a sample of liquid has a mass of 24 g and a volume of 16 mL. What is its density?
2.9 g/cm 3 A piece of metal has a mass of 43.5 g and a volume of 15 cm 3. What is its density? Practice Problem
By comparing densities, you can predict whether an object will sink or float in a fluid. An object that is more dense than the fluid it is in sinks. An object that is less dense than the fluid it is in floats on the surface An object with a density equal to that of the fluid floats at a constant depth.
Ability to float Ships are designed to have buoyancy
The pressure on the bottom of a submerged object is greater than the pressure on the top. The result is a net force in the upward direction.
The buoyant force works opposite the weight of an object.
Archimedes’ principle states that the buoyant force acting on a submerged object is equal to the weight of the fluid the object displaces.
A solid block of steel sinks in water. A steel ship with the same weight floats on the surface.
What is the volume of a box with the dimensions 8cm by 5cm by 5cm? 8cm x 5cm x 5cm = 200 cm 3
What is the volume of the dinosaur? 5.6mL-4.8mL = 0.8mL
If an object has a mass of 20 g and a volume of 40 cm 3, what is its density? 0.5 g/cm 3 Water has a density of 1.0 g/cm 3. If the object described above were placed in water, will it sink or float? Float!