2. LIFT
• Lift is the force that acts upward against gravity and makes it
possible for heavier-than-air aircraft to rise in the air
• When you fly a kite, the wind compresses air against the kite,
pushing it upward and keeping it aloft.
3. DRAG
• Drag is air resistance
• This resistance opposes an aircrafts motion through the air
• Drag is useful when you want to slow an object down such as
an airplane or space shuttle
• Space shuttles use parachutes to create drag
• You don't notice the air's drag when you walk or run. But you
feel the force of drag when you try to move through water. Fish
and dolphins must have a streamlined shape to reduce their
drag.
http://www.fi.edu/flights/own2/drag.html
4. WEIGHT
• Weight is the force generated by the gravitational attraction of
the earth on the airplane.
• When an airplane takes off the weight of the airplane is
calculated very carefully or the plane may not be able to take
off.
http://www.grc.nasa.gov/WWW/K-12/airplane/weight1.html
5. THRUST
•Thrust is the force which moves an aircraft through the air.
•Thrust is used to overcome the drag of an airplane, and to
overcome the weight of a rocket.
•Thrust is generated by the engines of the aircraft through some
kind of propulsion system.
http://www.grc.nasa.gov/WWW/K-12/airplane/thrust1.html
6. Relationships between the forces of lift, weight,
thrust, and drag that are required for flight
• lift must be greater than weight for a plane to take off
• thrust must be greater than drag for a plane to take off
• lift must be less than weight for a plane to land
• thrust must be less than drag for a plane to land
