Pascal's Principle, Bernoulli's Principle, Hydraulic Systems, Pressure and Moving Fluids
As the wind speeds up, what happens to the speed of the rising smoke in the chimney. Explain why this happens.
As the wind speeds up, pressure on top of the chimney will decrease, accourding to bernoulli's principle. Smoke will move up faster, going from a higher pressure area at the bottom of the chimney to a lower pressure area near the top of the chimney.
Why are hydraulic systems so efficient?
Because they use fluids to transmit pressure, they have few moving parts that can jam, break, or wear down.
Formula for Pressure?
Force/Area
Who is Blaise Pascal?
He was a French mathematician from the 1600's.
How does a hydraulic system work?
It multiplies force by applying the force to a small surface area (smaller piston). The increase in pressure is then transmitted to another part of the confined fluid, which pushes on a larger surface area (larger piston).
Why does smoke rise up the chimney?
Partly becaus hot air rises and partly because wind lowers the pressure above the chimney and higher air pressure at the bottom pushes air and smoke upward
What word should be associated with Pascal's principle? Bernoulli's?
Pascal=hydraulic Bernoulli=air
How does an atomizer work?
Squeezing an atomizer's bulb creates a difference between the top and bottom of its tube. The higher pressure at the bottom of the tube pushes perfume up tube and into stream of air moving out of it
Suppose you apply a 10N force to a 10 cm^2 piston in a hydraulic device. If the force is transmitted to another piston with an area of 100 cm^2, by how much will the force be multiplied?
The force will be multiplied by 10 because the surface area of the larger piston is 10 times greater. Therefore, the larger piston will apply a force 100N.
Why will a fluid exert pressure on any surface it touches?
The particles that make up a fluid are always moving in all directions. When these particles collide with each other on another surface, they exert a force (pressure) on the surface.
When the two pistons have different surface areas, how will the force exerted on them compare?
The piston with the greater surface area will experience a larger force.
When the two pistons have different surface areas, how will the pressure exerted on them compare?
The piston with the greater surface area will experience more pressure.
What did David Bernoulli discover?
The pressure of a moving fluid is different than the pressure of a fluid at rest.
What happens if you squeeze a water bottle when its top is closed?
The water has nowhere to go, so it presses harder on the inside surface of the bottle. The water pressure increases everywhere in the bottle.
When the two pistons have the same surface area, how will the force exerted on them compare?
They will experience the same force.
When the two pistons have the same surface area, how will the pressure they experience compare?
They will experience the same pressure.
How is it that a person can stop a large car with only a light push on the brake pedal?
This is possible because the brake system multiplies force.
On which part of a water bottle does the water exert pressure?
Water exerts pressure on the entire surface of the bottle.
What does Pascal's Principle state?
When force is applied to a confined fluid, the change in pressure is transmitted equally to all parts of the fluid.
How does Bernoulli's principle explain how a drinking straw works?
When you sip from a straw, an area of low pressure forms above the liquid. The liquid rises because of the low pressure above.
Describe the steps that happen in the brake system of a car from the time a driver steps on the brake pedal to the time the car stops.
a) A driver pushes down and exerts force on the brake pedal b)This moves the small brake pedal piston, which exerts increased pressure on the brake fluid c) The confined brake fluid transmits the increased pressure to larger pistons that push on the brake pads in the car's wheels d) The brake pads rub against the brake disc, and the wheel's motion is slowed down by the force of friction
What are four applications of Bernoulli's principle?
a) airplane wings b) atomizers c) chimneys d) flying discs
What are some examples of hydraulic systems?
a) lift systems b) brakes of a car
What are some uses for hydraulic lifts?
a) raise cars off the ground b) lift a heavy ladder on a fire truck c)to operate pieces of heavy construction pieces such as dump trucks, backhoes, snow ploes, and cranes
An airplane wing is designed to produce an upward force for a plane in flight. Why is the pressure lower above the wing?
a)As an airplane travels through the air, the wing's shape causes air above the wing to move faster than the air below b) the fast moving air exerts less pressure than the fast moving air c) as a result, the air pressure above the wing is lower than the air pressure below the wing, pushing up on the wing.
An airplane wing is curved at the top and flat on the bottom. Where will the air move faster?
above the wing
What is lift?
an upward force
An airplane wing is curved at the top and flat on the bottom. Where is the pressure greater?
below the wing
The spoiler on the back of a race car is shaped like an upside down wing. It is positioned above the rear tires. What does the spoiler do to the pressure on the rear wheels?
it increases the pressure on the rear wheels.
if you were to increase the curvature on top of an airplane wing, how would lift be affected?
it would increase
In a car's brake system there are two different pistons. What are they and which one is larger?
the brake pedal piston and the brake pad piston. The latter of which is larger.
What will happen if you blow a stream of air between two soda cans hanging on a rod?
the cans will move towards each other.
How does a fluid naturally flow?
A fluid naturally flows from an area of high pressure to an area of low pressure
How does a flying disc differ from an airplane wing?
A flying disc spins as it moves through the air, an airplane wing doesn't
What does Bernoulli's principle say about the pressure exerted by a moving fluid?
A principle that states that the faster a fluid moves, the less pressure the fluid exerts
Why is a leak in a hydraulic system a problem?
In order for pressure to be transmitted in a fluid, the fluid must be confined. If the hydraulic system is leaking, the fluid isn't confined.
What are the parts that make up a hydraulic device?
It consists of two pistons, one at each end of a U-shaped tube, and a confined fluid
What is a piston?
It is like a stopper that slides up and down in a tube
What is a hydraulic system?
It is one that uses a confined fluid to transmit pressure and multiply force.
What causes a hydraulic device to operate?
It is operated by the movement and force of a fluid.