Density and Buoyancy

1
Density and Buoyancy

• Chapter 11.2
• Page 424

2

• How can you predict if an object will sink or
  float in a fluid?

• You dive into a pool wearing a life vest. Wearing
  the vest makes you bigger and makes you weigh
  more. So why do you float?

3
Density and BuoyancyChapter 11. 2

• How can you predict whether an object will float
  or sink in a fluid?
• What is the effect of the buoyant force?

4
Density

• Density refers to the amount of matter that is
  contained in a certain amount of volume or space.
  It is better known as mass per unit volume.
• It is determined by first finding the mass and
  the volume of an object.
• Then, density is the mass of an object divided by
  its volume. Or
• Density __Mass__
• Volume

5
Density

• Changes in density cause a submarine to dive,
  rise, or float.

6
Density

• Changes in density cause a submarine to dive,
  rise, or float.

7
Density

• Changes in density cause a submarine to dive,
  rise, or float.

8
Buoyancy

• Buoyancy is the ability to float.
• A buoyant force acts on a submerged object in the
  opposite direction to the force of gravity.

9
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.

10
Buoyancy

• The buoyant force works opposite the weight of an
  object.

11
Buoyancy

• Archimedes principle states that the buoyant
  force acting on a submerged object is equal to
  the weight of the fluid the object displaces.

12
Buoyancy

• A solid block of steel sinks in water. A steel
  ship with the same weight floats on the surface.

13
Density

• Click the Video button to watch a movie about
  density.

14
End of SectionDensity and Buoyancy