Chap 12 : Force and Fluids >> Science

What is pressure?

The force per unit of area that is applied on the surface of an object

What factors affect pressure?

Increases as the force applied increases
Decreases if the area of contact increases

How is it calculated?

Pressure equals force divided by area

What is the unit for pressure?

Pascal (Pa)

How can weight be used to calculate pressure?

Force can be equal to the weight of an object, then divide weight by area

How is weight calculated

Weight = mass X acceleration due to gravity

How can the pressure exerted be changed?

Change the area over which the force is applied

What is the relationship between pressure and area?

Force applied to a small area = larger pressure

What is a fluid?

Any substance that has no definite shape and has the ability to flow

What are examples of fluids?

water, motor oil, and air

What are not an example of a fluid?


What is the relationship between pressure and fluid height?

The greater the height, the greater the pressure

What is the relationship between pressure and depth?

Deeper depth = increase in pressure; this is due to the increase of height and weight of the fluid above you

How does pressure affect objects in a fluid?

Is exerted on all sides, perpendicular to the surface of an object

What is atmospheric pressure?

A fluid constantly exerts pressure on objects

What levels atmospheric pressure at sea level?

100,000 Pa

What is a barometer do?

Used to measure atmospheric pressure

How do barometers work?

Height of the liquid column increased as the atmospheric pressure increase

What is buoyant force?

An upward force that is exerted by a fluid on any object in the fluid

What causes buoyant force?

By the pressure that is exerted by a fluid on an object in the fluid

What causes an object to sink?

If the weight of the object is greater than the buoyant force then the object will sink

What causes an object to float?

If the buoyant force is equal to the object's weight, the forces are balanced and the object will float

What are 2 buoyant force factors?

Shape and Depht

What is Archimedes principle and what does it determine?

the buoyant force on an object is equal to the weight of the fluid is displaced

What does Archimedes principle determine?

Determines if an object sinks or floats

What is density?

The mass of an object divided by the volume

How can density be calculated?

Density = mass / volume

What factors determine if an object will sink?

Sinking: occurs if the dense fluids to increase an input force sit is greater than the density of the fluid it's placed in

What factors determine if an object will float?

Floating: occurs if the density is less than the density of the fluid it's placed in

What happens when the mass of a steel object and boat are the same but the volume if the boat is much larger?

The boat will float because the large volume results in a lesser density than water

What are fluid forces?

Can be made to exert forces to do useful work; pumping water from well, cars stopping

How to increase fluid forces

Can be increased by pushing on the fluid

What is pascal's principle

When a force is applied to a fluid in a closed container, the pressure in the fluid increases by the same amount

what is an example of Pascals Principle

squeezing water out of a bottle

What is an hydraulic system and how does it work?

Fluid transfers pressure from one piston to another

What is Bernoulli's principle

the speed of a fluid increases, the pressure of the fluid decreases
Faster = less pressure

What is lift?

Upward force on an airplane's wings

How is lift created?

By making the air flow downward

What factors determine the amount of lift a plan will have?

Depends on the amount of air that the wing deflects downward
By increasing the size or surface area of the wing

What are some different wing types and how do they impact flight?

Glider = long, narrow to glide long distances
Jet fighter = small, narrow, tapered for high speeds