Different types of racing and the Physics
Different types of racing and the Physics
    Drag racing has always been a passion of many people across the world.  The 4.5 s’s of
speed and adrenaline has enticed many people to acquire a car to race in this style.  The physics
involved in general are simply and easy to understand.  NASCAR Winston Cup Racing is the
fastest growing spectator sport in America today with an alarming number of fans.  These fans,
though they probably do not realise it, are experiencing a display of fantastic physics at work.
Every aspect of the sport involves physics, from the car to the jack that is used to hoist the car
up.  The physics is fascinating and involves knowledge of the field of fluid dynamics,
aerodynamics and engineering.   
                          Drag Racing
    You are sitting in your drag racing car waiting for the green light to shine and for you to
start your 4.5 s jaunt down a quarter mile strip of asphalt.  The green light flashes on and you put
you foot down hard onto the gas pedal.  The tires wrinkle from the pressure and with the low air
pressure they are able to grip the asphalt with ease.  As the back tired grip the front ones lift off
the quarter mile track until sufficient down force is supplied on the car.  At 0.4 s the tires inflate
more (Popular Science credits this expansion to centrifugal forces) because of Newton’s law.
Significant force is supplied to tired and tired push back at the forces.  The tires increase from
91.4 cm (36 in) to 109.2 cm (43 in).  At 0.6 s the drivers start to experience forces of up to 4.5
G’s.  After 1.1s the downforce is prevalent along the chassis of the car creating more power in
the back of the dragster.  At 1.2s the car has achieved a speed of 67 m/s (150mph) and has
travelled a distance of 61m (200ft).  3.5 s marks travelling 198m (650ft) and achieving a speed
of 122.9m/s (275 mph) and 4.0s marks 125 m/s (300mph) at a distance of 305 m (1 000 ft).
Finally after 4.5s the chute is released for the driver to experience up to 4.5 G’s of force again
during deceleration. 
                             NASCAR
Circular or oval racing is more complex.  The cars are running on asphalt surfaces in oval or tri-
oval settings on a regular basis.  The cars, which weight 1542 kg (3400lbs), are designed to limit
drag and lift but maintain down force to maximise the speed. For example if you were to take
Chicagoland Speedway and pretend that it is a circular track with constant banking of 18 degrees
you could figure out that the cars are going faster than to maintain a circle of a constant radius.
(See Figure 1)
Figure 1






















    NASCAR drivers, though they may not be aware of it deal with forces on a daily basis.
Unconsciously they diminish speed going into corners so that they slide down the track towards
the centre where the distance they travel is less in hope of getting ahead of the competitors.  On
front and back straightaways the banking is less so as the speed increases the cars go up the
track.  However, the speed increase is more beneficial than staying to the bottom of the track
which has less distance.  (See Figure 2)

Figure 2


















    NASCAR teams increasingly are hiring aerodynamicists and engineers to help gain
advantages over the competition on the track.  An advantage as small as 0.1 s or smaller can be
significant over the duration of 500 miles (805km).  There are standards put into place by
NASCAR officials so it is challenging to make significant improvements to the car.    There are
templates used to ensure the cars conform to the rules and every car must go through pre-race
inspection and certain cars must go through post-race inspection.  These rules goven spoiler
height which can be used to increase downforce which makes it so there is more force applied to
the track making it so the cars can go faster without travelling up the track ( increasing friction).
These rules also goven how high the car must be off the track.  If the car is sufficiently low then
less air travelles below the car.  Air below the car can cause lift which is what keeps planes in
the air.  By making the car lower to the ground it decreses the lift on the car.  By minimising life
and maximising downforce you are able to create more friction allowing the cars to stay lower
on the track with an increased speed.
    Drivers also use the technique of drafting to lessen the air resistance creating an
environment without air resistance making the care move faster.  This technique is employed by
driving your car right behind the car in front of you so the front car plows through the air so the
front of your car does not have to plow through the wall of air. (See figure 3)


Figure 3


























    To make a realistic “feeling” of what air resistance feels like, drive down a highway and
sick one hand out the window. First, put your hand out flat, then upright (see Figure 4)
Figure 4











    Notice that when your hand is flat that you feel little air resistance compared to when
your hand is upright.
    In conclusion, NASCAR has many complex pieces which involve knowledge of fluid
mechanics in the field of physics. These fluid mechanics are also used when designing smoke
stacks and buildings to ensure that they can with hold the wind pressure and for planes so that
they don’t fall out of the sky.  The application of fluid dynamics is interesting in realistic settings
such as within the sport of NASCAR.