Buoyancy & Aerodynamics

WHY THINGS FLOAT AND FLY Jeff Rhoads & Terry Ballinger MST @ MSU 2006

Outline  Introduction  What is a Fluid?

 Aerodynamics  Buoyancy  Today’s Activity

Introduction  Aerodynamics – Why things fly  Lift  Drag  Buoyancy – Why things float  Density  Volume Displaced

… concepts involve fluids .

What is a Fluid?

What is a Fluid?

 A substance tending to flow or conform the outline of its container to What are some other examples?

Aerodynamics

Aerodynamics  The study of forces and the resulting objects that move through the air . motion of … drag & lift are important.

Example: Jet Airliner … drag & lift are important.

Drag  Opposing force (opposite to direction of travel) due to motion through the air

Drag  Opposing force (opposite to direction of travel) due to motion through the air

Friction Drag

Drag  Opposing force (opposite to direction of travel) due to motion through the air

Friction Drag Pressure Drag

Lift  Upward force due to motion through the air

Lift  Upward force due to motion through the air

Why it Flies

Lift Force



Weight

Buoyancy

Buoyancy  The tendency of a body to float or to rise when submerged in a fluid

Archimedes Principle  A body immersed in a fluid is buoyed up by a force equal to the weight of the fluid it displaces.

Buoyancy Force  Weight of Displaced Fluid

Will it Float?

Object What forces act on the object?

Will it Float?

W

 Weight

B

 Buoyancy Force

Will it Float?

W

 Weight

B

 Weight of Displaced Fluid   Archimedes  Principle 

Will it Float?

W

 Weight

B

 Mass of Displaced Fluid  Gravity

Will it Float?

W

 Weight

B

 Density Displaced of  Volume  Gravity Mass of Disp. Fluid

Will it Float?

W

 Density of Object  Volume Mass of Object  Gravity

B

 Density Displaced of  Volume  Gravity Mass of Disp. Fluid

Will it Float?

Object Density  Disp.

Fluid Density

Will it Float?

Object Object Density  Disp.

Fluid Density Object Hovers

Will it Float?

Object Density  Disp.

Fluid Density

Will it Float?

Object Object Density  Disp.

Fluid Density Object Ascends

Will it Float?

Object Density  Disp.

Fluid Density

Will it Float?

Object Object Density  Disp.

Fluid Density Object Sinks

Example: A Ship USS Dwight D. Eisenhower Weight: 95,000 tons

Today’s Activity: Airplanes!

Objective Create a set of paper airplanes capable of traveling the furthest, staying aloft the longest, and …