Brakes and Pascal's Principle

From Wikipedia: "Pascal's law, or the Principle of transmission of fluid-pressure, states that "Pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid, such that the pressure ratio remains the same."

For brakes or hydraulic lifts, the idea is simple. Apply a force (F1) through a small area (A1) and the pressure (P) is given by F1/A1.

The pressure is transmitted through the fluid equally. The pressure on the other side, onto another piston (area A2) will generate a force (F2). P = F2/A2

Since the pressures are constant:

F1/A1 = F2/A2

Some interesting pages to view:

http://www.mrwaynesclass.com/teacher/Fluids/hydraulics/home.html

http://physics.bu.edu/~duffy/semester1/c23_pressure_pascal.html

http://www.youtube.com/watch?v=VxLTDtaRCZk

http://www.yteach.co.uk/page.php/resources/view_all?id=p5_pressure_force_area_load_Pascal_compression_strength_t&from=search

for a more mathy approach

http://www.youtube.com/watch?v=A3ormYVZMXE&feature=related

Engines revisited - what happens when you turn the key?

Recall this video from class.

http://www.howstuffworks.com/engine.htm

See the cut-away engine animation:

http://auto.howstuffworks.com/engine1.htm

A first look at what happens when you turn a key.

1. Turn key

2. Current runs to starter (through solenoid) - this creates a magnetic field which engages the starter.

3. Starter motor turns engine and triggers a series of events.

4. Coil takes current from battery and increases voltage (it is essentially a transformer) - the voltage is applied to the distributor.

5. The distributor allocates voltage to each spark plug in the correct firing order.

(6. The alternator replenishes the battery.)

7. The electrical spark from the spark plug ignites the compressed fuel mixture (brought in during INTAKE STROKE), driving the piston downward (away from plug). This is the POWER (or combustion) STROKE.

8. Piston is driven upward - exhaust gases are expelled. EXHAUST STROKE

9. Fuel mixture is brought into cylinder, due to pressure differential and fuel mixture sent in through carburetor,. INTAKE STROKE

10. Piston is compressed again. COMPRESSION STROKE.

Piston motion is linear, but this is converted to rotary motion via crankshaft.


SEE VIDEO:

http://auto.howstuffworks.com/engine1.htm

http://auto.howstuffworks.com/engine2.htm


Furthermore:

Engines use water and air to dissipate the huge amount of heat generated. The pump moves water around the cylinder walls and valve jackets. Heat is transferred to water and water is pumped back to radiator. The hot water is cooled by air convection and cool water is pumped back to engine.

Oil is used to decrease friction caused by metal on metal. The oil pump circulates the oil to critical areas in the engine. An oil filter cleans the air, removing dirt and particles. The fuel pump pushes gas into the carburetor, which introduces air and creates a fuel-air mixture that travels into the cylinder chamber.

Adapted from Auto Repair by John Doyle, 1987.

Functions in the 4-stroke engine

4 Stroke Engine Parts

Reminder

Papers are due Friday, even though we have class tomorrow.

I will also accept some other form of descriptive device: poster, movie, etc.

The important thing is that you explain your system or piece of technology. At least one image should be included.

Good luck!