Physical Principles

Question 1

Aerodynamics definition

Answer 1

The study of the behavior of moving air and the forces that it produces.

Question 2

What is a force?

Answer 2

Force – Intensity of push or pull on an object, whether it moves or not. No “work” is done until object moves in direction of force – sideways motion does not count
●Defined by size and direction
●f = ma (Newton’s 2nd law) Force = mass x acceleration
●Expressed in pounds (lbs)

Question 3

What are the 3 forces?

Answer 3

Thrust – moves aircraft forward through air
Weight – downward force
Aerodynamic force – result of air pressure
●Resolved into two forces of Lift and Drag
End result is four forces

Question 4

Use of vectors

Answer 4

Forces are shown using vectors to show quantity and direction
●Vector addition
●Vector resolution

Question 5

Moment (torque)

Answer 5

A rotational force that results from applying a force away from the point of rotation
●Moment = F x length of moment arm
●Expressed in foot-lbs (ft.-lb.)

Question 6

Plane moments

Answer 6

Pitch, yaw, and roll.

Question 7

Newton’s first law

Answer 7

Law 1 – object at rest stays at rest an object in motion stays in motion until…
●Inertia – body’s resistance to change
●Speed – how fast a body is going
●Velocity – how fast a body is going in a certain direction
Units = feet/sec or fps
●Acceleration – how fast velocity is changing
Units = feet/sec2 or fps2

Question 8

Newton’s second law

Answer 8

Law 2 – If a force acts on a body, the body will accelerate in directional of force under the following criteria…
●acceleration = Force/mass of object
f = ma
●Mass = amount of material in an object
Expressed in pounds?
●Slug = English unit of mass
32 lbs of weight is 1 slug, units =
32 fps2 is gravitational constant

Question 9

Newton’s third law

Answer 9

For every action there is an equal and opposite reaction.

Question 10

Work, energy, and power

Answer 10

Work – Force x Distance
●If you apply a force but nothing moves, has any work been done?

Energy – ability to do work
●Lots of types, we will focus mostly on mechanical

Power – Rate(speed) of doing work
●Energy expended per second

Question 11

Law of conservation of energy

Answer 11

The amount of energy always remains the same, it just changes forms.

Question 12

Mechanical energy

Answer 12

ET=EP+EK

Potential Energy –
●Stored Energy (Energy of Position)

Kinetic Energy –
●Energy of Motion

As an object falls –
EK increases, EP decreases
EP just before release is equal to EK at impact.