chapter 3 Flashcards
(23 cards)
what is newton’s law of motion govern ?
the conservation of momentum
what is Bernoulli’s equation derived from?
the law of conservation of energy
how does lift occur? explain
when a flow of gas is turned by a solid object. The flow is turned in one direction and the lift is generated in the opposite direction
because air is a gas and the molecules are free to move about, can any sold object deflect a flow?
yes
What are some components of generating lift?
momentum, conserving the mass, and energy in the flow.
Define Euler equation?
Who is named after?
The simultaneous conservation of mass, momentum, and energy of a fluid while ignoring the effects of viscosity.
Leonard Euler
True or false. lift is generated by a force field through a gravitational force or electromagnetic field.
False. Lift is a mechanical force. In order for lift to be generated the solid body must be in contact with the fluid (liquid or gas); no fluid, no lift. Without air, there is no lift generated by the wings of an aircraft.
Is lift generated by the difference in velocity between the solid object and the fluid?
yes
True or False: In relation to lift it makes no difference weather the object moved through a static fluid, or the fluid moves past a static object
true
lift act ____ to the fluid motion while drag acts in the direction ____ to the motion
perpendicular
opposed
what does the lift equation take into account?
the dependence of life on the square of the velocity, the surface area, the shape of the object, inclination of the object to the flow, and the properties of the air.
What is newton’s first law?
every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by forces impressed on it.
Newton’s second law
force is equal to the change in momentum per change in time. For a constant mass, force equals mass time acceleration
When a body is acted upon a constant force, it resulting acceleration in ___ proportional to the mass of the body and is ___proportional to the applied force.
inversely
directly
What does Newton’s 2nd law cover?
both changes in direction and speed, including starting up from rest (positive acceleration) and coming to a stop (negative acceleration, or deceleration).
Newton’s third law?
For every action there is an equal and opposite reaction
In relation to composition of the atmosphere which exerts a mixture of gasses that are governed by the laws of fluid motion. When flowing, each particle’s ___ and ____ are variable, and the path they take is called ______
velocity
direction
stream line
How do you form a stream tube?
multiple streamlines flowing adjacent to each other
What is a stream tube?
is a closed system within which mass is conserved (neither created or destroyed., but can be transformed from one type to another
The mass of air entering the stream tube in a given unit of time exactly equals the mass of air exiting, much like water flowing through a garden hose. How would you find the mass flow?
Mass flow (Q)in slugs per second = multiple cross sectional area of the stream tube (A) by the velocity (v) and the density of the gas (p) such that Q=pAv
what is the mass continuity equation used for?
used to explain variations in airflow velocity through varying cross-sectional areas.
What is ignored for subsonic flow?
the effects of compressibility are ignored since subsonic flow is incompressible.
What happens with incompressible flow?
the density of a fluid is constant and will not change from one location to another.
