AUTOMOBILE - LAB
Identify where car power comes from, and why.
A car is a complex compound machine, that
is fueled by gasoline to create motion. In a car, the engine is
responsible for producing the power that causes the wheels to turn.
The engine turns a rod called a crankshaft which is connected to the
drive shaft which in turn is connected to the axle which of course is
connected to the wheels.
Gasoline is pumped into the gas tank of
the car. From the gas tank, the fuel travels through the fuel line
and reaches either the carburetor or fuel injector. From this
point the gas flow is controlled by the amount of pressure placed on the
accelerator. The fuel is converted into a mist much like a perfume
by the carburetor. This "perfume" is then released into the
cylinders where it is compressed, ignited, and exploded. Each time
an explosion takes place the pistons are forced down, causing the
crankshaft to turn. With each turn of the crankshaft comes a turn
of the driveshaft and with each turn of the driveshaft, comes a turn of
the axle and consequently the wheels.
A car is a complicated and complex
machine that is dependent upon the laws of physics for both efficiency
and performance. Nearly all the laws of physics can be found in
the workings of an automobile. Friction between the rubber tires
and asphalt ground is the reason why the car moves (aside from all the
workings of the engine). To better improve friction, tires
are built and designed with tread patterns that grip the asphalt road
Aerodynamics is also a great factor when
it comes to designing cars. Air resistance can contribute greatly
to low gas mileage and poor efficiency. As a result, car
manufacturers design automobiles with pointed fronts, rounded bodies,
and streamlined patterns. With these designs the air can be "cut"
so that it does not act like a block stopping the car. A good way
to test the notion of air resistance is to put a hand out of a car when
going down the freeway. A vertical hand pointing straight up will
encounter great air resistance while a horizontal hand will encounter
hardly any. This is the reason why cars are pointed in the front
and not flat.
Work done by the engine is transferred to
different parts of the car through gears and levers until this work
reaches the axle. Once the work has reached the axle the tires can
be turned and the car can move. For this work to be created,
however, requires the presence of such items as carburetors,
pistons, crankshafts, spark plugs, gasoline, and many other components.
A car is about the best example of all the forces of physics coming
together for one purpose, motion.