Today

Folks,

I'm out again today.  Please begin work on your historical paper.  If you have doubts as to whether or not I'll approve the paper, email me.

I expect to be back by Friday's class, and we'll do some work then.  I believe all go-cart parts are in, and the Geely scooter stuff, too.

Thank you.

Sean

Sean out today

Folks - I'm out today.  Here's what you should be doing:

Revisit the sites below (particularly the 4-stroke engine ones).  Watch the animation and be sure to read the howstuffworks pages.

Also, come to class on Wednesday with a potential historical topic for your final paper.  Plan on this being a 5-7 page paper on a topic of automotive historical significance.

I hope to be back by Wednesday.  Sorry to be out.

Engines vs. Motors

http://www.youtube.com/watch?v=FfTX88Sv4I8

http://www.youtube.com/watch?v=XVdZj2EDmhM
with labels

http://www.youtube.com/watch?v=aATDsYVVcRM&feature=fvwrel

http://www.animatedengines.com/otto.html
Otto Cycle

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

Alternate pages for the animation:

http://www.poetv.com/video.php?vid=8037

http://videosift.com/video/Animation-of-car-engine-assembly-and-operation

More info than you need:

http://en.wikipedia.org/wiki/Engine

Motors:

http://www.animations.physics.unsw.edu.au/jw/electricmotors.html

FYI

http://www.mopedcentral.com/forsale.html

For those of you looking to buy something - this guy buys and sells project mopeds.

Fun, from class

http://www.youtube.com/watch?v=dJfSS0ZXYdo

http://www.youtube.com/watch?v=QQh56geU0X8

Pascal's Principle - the secret of brakes

In general, most fluids are incompressible (or very slightly compressible).  As a result, pressure applied to a fluid is transferred equally everywhere in the fluid.  Recall the definition of pressure:

P = F / A

Pressure = force / area

The units could be psi (pounds per square inch), or (in SI units), newtons per square meter (also called a pascal, Pa).

Force (F1) is applied to the small piston (A1), yielding a certain pressure (P).  This is transmitted to the secondary piston (A2).  To keep the ratio (P) constant, the resulting force (F2) on the other piston must be proportionally larger.  This can be used to lift large objects (auto lifts) or stop fast cars with the application of your feet.

FYI:

http://hyperphysics.phy-astr.gsu.edu/hbase/pasc.html

Related:  Pascal's law



The change in pressure equals the density times g (9.8 m/s/s) times the change in vertical height - this is useful for determining the pressure difference between two very different altitudes.


Now about those brakes....

Imagine pushing on brakes.

Fluid is transferred through brake lines to either drums or discs:

http://hogantire.com/tcbrakes.htm

http://auto.howstuffworks.com/auto-parts/brakes/brake-types/brake.htm

More from today's class

The Bernoulli Principle:

The pressure in a "moving stream" of fluid is LESS than that of the surrounding fluid.  Recall the demonstrations:

- blowing between the 2 soda cans
- the beach ball suspended by the air from the shop vac
- imagine putting your thumb over the nozzle from a garden hose

The last example relates to the "equation of continuity" -

A1 v1 = A2 v2

Meaning:  As the area (of the tube) gets smaller, the speed of the fluid gets greater.

Videos for the carburetor:

http://www.youtube.com/watch?v=4MnOgR4_jaE

http://www.fz1-forum.com/forum/gen-i-garage-tech-help/13659-how-carburetor-works-short-animation.html