Lift | Drag | Thrust | Gravity | Bernoulli's Principle | The Venturi Effect | Newton's Law's | The Truth about Bernoulli
This states: As the speed of a fluid increases, the pressure inside the fluid, or exerted by the fluid, decreases.
This means that
if water flows through a horizontal pipe of varying width, the water must flow faster in
the narrower regions. The pressure on the water must be greater in the wider regions,
because the walls of the pipe must exert a force to accelerate the water on its way to the
narrower width.
Bernoulli's law
explains the lift that permits airplanes to fly. When air particles hit the airfoil, they
must split and go either over the top or under the bottom. Particles going over the top
have to move faster than those underneath. This is because they have to go much farther to
reach the trailing edge at the same time. Because air that is moving faster has less
pressure (Bernoulli’s law) this rush of air over the top of the wing causes the
airplane to lift.
T h e V e n t u r i E f f e c t
An example of this would be a hairdryer and a ball. If
you placed the ball onto the hairdryer and then turned it on, the ball would lift into the
air. This is not because the air is pushing the ball up, but rather because the air is
being blocked by the ball and therefore rushing around it (creating lift), keeping it in
the air.
Demonstrate this to your friends by taking a long strip of paper and holding it
to your mouth and blowing it. The paper should rise into the air.
First law of
motion (Law of inertia)
Second law of
motion (Law of force and mass)
Third law of
motion (Law of action and reaction)
Newton’s
first law of motion states that any object in a state of rest tends to remain in rest
unless acted upon by an unbalanced external force. In effect, this is a definition of
equilibrium. The tendency for matter to
maintain its state of motion is known as inertia.
Newton’s second law of motion states that an unbalanced force acting on a object produces an acceleration that is in the direction of the force, directly proportional to the force, and inversely proportional to the mass of the object. In simpler terms , force equals mass times acceleration, or F = ma. This means that a given force will accelerate an object of small mass more rapidly than it will an object of larger mass. Similarly, doubling the applied force produces twice the acceleration of an object of the same mass.
Newton’s third law of motion states that every action (or force) gives rise to a reaction (or opposing force) of equal strength but opposite direction. In simpler terms, every object that exerts a force on another object is always acted upon by an equal and opposite reaction force. And example of this would be a rocket.
T h e T r u t h a b o u t B e r n o u l l i
During World war 1, Albert Einstein developed a wing that was so bad it hardly flew. He said that he had based his design on
Bernoulli’s principle and not on the energy conservation, particle and coalescence
theories. In 1954 he wrote: “ Although
it is probably true that the principle of flight can be simply explained by this
(Bernoulli’s principle), it is not wise to construct a wing in this manner!”
It was later discovered that only 5% of all lift came from
Bernoulli’s principle. So where does the
rest come from?
According to Newton’s 3rd law of motion for a wing to supply lift it must have something to push down. This means to get lift the wing must push the air down.
It was later discovered that only 5% of all lift
came from Bernoulli’s principle. So
where does the rest come from?
Now think of a pool table...
If we roll a ball at the side, it bounces off. If we were to measure the speed of the ball we
would find that it looses speed after hitting the table.
This is because it gives away some of
it’s energy to the table.
This is part of the law of energy conservation.
Now what would happen if we put a box on the pool table and
rolled balls at it. Each time a ball hits the box,
some of its energy is transferred to the box and the box moves a bit.
The same thing happens to an aeroplane: When air particles hit the bottom surface of the wing, they bounce off and are deflected downward. Some of their energy is given to the wing, pushing it upwards and backwards. This is what we call LIFT and DRAG.
" We shall not cease from exploration and the end of all our exploring will be to arrive where we started and to know the place for the first time. "
Anon