Velocity (pronounced vuh-los-i-tee)
(1) Rapidity of motion or operation; swiftness; a
certain measurement of speed.
(2) In mechanics and physics, a measure of the
rate of motion of a body expressed as the rate of change of its position in a
particular direction with time. It is
measured in metres per second, miles per hour etc.
(3) In casual, non technical use, a synonym for
speed.
1540-1550: From the Middle French vélocité, from the Latin velocitatem (nominative vēlōcitās) (swiftness; speed), from vēlōx (genitive velocis) (swift, speedy, rapid, quick) of uncertain origin. It may be related either to volō (I fly), volāre (to fly) or vehere (carry) from the primitive Indo-European weǵh- (to go, move, transport in a vehicle) although some etymologists prefer a link with the Proto-Italic weksloks from the primitive Indo-European weg-slo-, a suffixed form of the root weg- (to be strong, be lively). Although in casual use, velocity and speed are often used interchangeably, their meanings differ. Speed is a scalar quantity referring to how fast an object is moving; the rate at which an object covers distance. Velocity is the rate at which an object changes position in a certain direction. It is calculated by the displacement of space per a unit of time in a certain direction. Velocity deals with direction, while speed does not. In summary, velocity is speed with a direction, while speed does not have a direction. Velocity is a noun; the noun plural is velocities.
Great moments in velocity stacks
Velocity stacks (also informally known as
trumpets or air horns) are trumpet-shaped devices, sometimes of differing
lengths, fitted to the air entry of an engine's induction system, feeding
carburetors or fuel injection. Velocity
stacks permit a smooth and even flow of air into the intake tract at high
velocities with the air-stream adhering to the pipe walls, a process known as
laminar flow. They allow engineers to
modify the dynamic tuning range of the intake tract by functioning as a
resonating pipe which can adjust the frequency of pressure pulses based on its
length within the tract. Depending on
the length and shape of the stack, the flow can be optimized for the desired
power and torque characteristics, thus their popularity in competition where the
quest is often for top-end power but the flow can also be tuned instead to
produce enhanced low or mid-range performance for specialized use.
The 1968 McLaren M8A was built for the Canadian-American Challenge Cup
(the Can-Am) and used a new aluminum version (later sold for street use as the ZL1) of the 427 cubic inch (7.0
litre) big-block Chevrolet V8. Dry
sumped and fuel injected, it was rated at 625 bhp. A series for unlimited displacement sports
cars, the wonderful thing about the Can-Am was the brevity of the rules which
essentially were limited to (1) enclosed body work and (2) two seats (one of which was close to a fake). With engines eventually growing beyond 490 cid
(8.0 litres) and reaching close to 800 horsepower, the McLarens dominated the series for five years, their era ended
only by the arrival of the turbo-panzers, the turbocharged Porsche 917s which in qualifying trim generated a reputed 1500 horsepower. The McLarens remained competitive however, the final race of the 1974 series won by a McLaren M20.
Ferrari built 25 512S models in 1969-1970 to
comply with the FIA’s homologation rules as a Group 5 sports car to contest the
1970 International Championship for Makes.
It used a five-litre V12 and was later modified to become the 512M which, other than modified road cars, was the last Ferrari built for sports car racing, the factory instead focusing
on Formula One.
Coventry Climax developed their FWMW between
1963-1965, intending it for use in Formula One.
A 1.5 litre flat-16, both the Brabham and Lotus teams designed cars for
this engine but it was never raced and the engines never proceeded beyond the
prototype stage. Like many of the exotic
and elaborate designs to which engineers of the era were attracted, the
disadvantages imposed by the sheer bulk and internal friction were never
overcome and the promised power increases existed in such a narrow power band
it’s usefulness in competition was negligible.
Even on the test-benches it was troublesome, the torsional vibrations of
the long crankshaft once destroying an engine undergoing testing. It was Coventry at its climax; after the débacle of the FWMW, the company withdrew from Formula One, never to return.
Porsche developed their flat-16 in the search
for the power needed to compete with the big-capacity machines in the
Can-Am series. Unable further to enlarge their
flat-12, their solution was to add a third more cylinders. As an engine, it was a success and delivered
the promised power but the additional length of the engine necessitated adding
to the wheelbase of the cars and that upset their balance, drivers finding
them unstable. Porsche mothballed the flat-16 and resorted instead to forced-aspiration, the turbocharged flat-12 so
effective that ultimately it was banned but not before it was tweaked to deliver a reputed 1500+ horsepower in Can-Am qualifying trim and, in 1975, at the Talladega raceway it was used to set the FIA closed course speed record at 221.160 mph (355.923 km/h); the mark stood for five years.
Not all the Ford
GT40s had the photogenic cluster of eight velocity stacks. When the Ford team arrived at Le Mans in
1966, their Mk II GT40s were fitted with a detuned version of the 427 cubic inch (7.0 litre)
big-block FE engines used on the NASCAR circuits and instead of the multiple twin-choke
carburetors with the velocity stacks familiar to the Europeans, it was fed by
a single four barrel unit under a fairly agricultural looking air intake. On the GT40s, the velocity stacks looked best
on the 289 and 302 cubic inch (4.7 & 4.9 litre) small-block Windsor V8s,
the ones built with the four downdraft Weber carburetors thought most charismatic.
In typically English fashion, the 1949 BRM V16 is celebrated as a
glorious failure. In grand prix racing,
it failed for many reasons but in one aspect, it was a great success: the supercharged 1.5 litre engine generated prodigious, if hard to handle, power. Not discouraged,
when a three litre formula was announced for 1966, BRM again found the lure of
sixteen cylinders irresistible though this time, aspiration would be
atmospheric. It actually powered a Lotus
to one grand prix victory in Formula One but that was its sole success. Although nice and short, it was heavy and it
was tall, the latter characteristic contributing to a high centre of gravity,
exacerbated by the need to elevate the mounting of the block to make
space for the exhaust system of the lower eight cylinders. It was also too heavy and the additional
power it produced was never enough to offset the many drawbacks. Withdrawn from competition after two seasons
and replaced by a more conventional V12, the FIA later changed the rules to
protect BRM from themselves, banning sixteen cylinder engines.
Build to comply with Group 6 regulations for prototype sports cars, the Ferrari 312 P was raced by the factory towards the end of the classic era for sports car racing which dated back to the early 1950s. Fielded first with a three litre V12, it was re-powered with a flat-12 in 1971 and has often been described as the Ferrari Formula One car with bodywork and while a simplification, given the engineering differences between the two, that was the concept. It appeared on the grid to contest the World Sportscar Championship in 1969, a return from a year of self-imposed exile after one of Enzo Ferrari's many arguments with the FIA. Needing reliability for distance racing, the Formula One engine was slightly detuned and, as in the open wheeler on which it was based, acted as an integral load-bearing part of the structure. Unlike Ferrari's earlier sports cars, this time the classic array of Webber carburetors was eschewed, the velocity stacks sitting atop Lucas mechanical fuel-injection.
Albert
Einstein, Lindsay Lohan and velocity
Velocity
plays is a critical component in Albert Einstein’s (1879-1955) Special (1905) &
General (1915) Theories of Relativity. ,
profoundly influencing our understanding of space, time, and gravity. In the Special Theory of Relativity, there is
an explanation of the perception of “simultaneity”: events simultaneous in one
frame of reference may not be simultaneous in another frame moving at a
different velocity. The critical
implication of this wais that time was absolute but depends on the relative
motion of observers. This means a moving
clock runs slower than one which is static (relative to the observer). History’s second most quoted equation (number
one said to be “2+2=4” although this is contested) is Einstein’s expression of
mass-energy equivalence (E=mc2) which shows that mass and energy are
interchangeable. The significance in
that of velocity is that as an object's velocity approaches the speed of light,
its relativistic mass increases, requiring more energy to continue
accelerating. From this Einstein deduced
the speed of light was the “universal speed limit” because for this eventually to
be exceeded would require the input of an infinite amount of energy. Whether such a state might have been possible
in the first fraction of a second during the creation of the current universe remains
a matter of speculation but as it now exists, the limit remains orthodox
science.
The role of
velocity in the General Theory of Relativity remains fundamental but is more
complex still. In addition to the
dilation of time sue to relative motion, there is also “Gravitational Time
Dilation” (due to relative motion, gravity itself causes time to dilate). Objects moving in strong gravitational fields
experience time more slowly than those existing in weaker fields. Radically, what Einstein did was explain
gravity not as a force (which is how we experience it) but as a curvature of
space-time caused by the effects of mass & energy and the motion (and thus
the velocity) of objects is is influenced by this curvature. The best known illustration of the concept is
that of “Geodesic Motion”: In curved space-time, a free-falling object moves
along a geodesic path (the straightest possible between the points of departure
& arrival). The velocity of an object influences its trajectory in curved
space-time, and this motion is determined by the curvature created by
mass-energy.
Two of Lindsay Lohan’s car most publicized car accidents. All else being equal (which, as Albert Einstein would have explained, probably can’t happen), if an object is travelling at a higher velocity (in the casual sense of "speed"), the damage will be greater. In these examples, at the point of impact, the Porsche 911 (997) Carrera S (2012, left) was travelling at a higher velocity than the Mercedes-Benz SL 65 AMG roadster (2005, right).
In classical (pre-Einstein) mechanics, the explanation would have been an object traveling at a higher velocity would have its kinetic energy increase quadratically with velocity (ie double the velocity and the kinetic energy increases by a factor of four. In relativistic physics, as an object's velocity approaches the speed of light, its relativistic mass increases with velocity and relativistic mass contributes to the object's total energy. For velocities much less than the speed of light (non-relativistic speeds (a car, even with Lindsay Lohan behind the wheel)), the increase in mass is negligible, and the primary difference is the increase in kinetic energy which follows the classical equation. However, at velocities approaching the speed of light, both the kinetic energy and the relativistic mass increase significantly. In a car crash, the main determinate of an impact's severity (and thus the damage suffered) is the kinetic energy: A car traveling at a higher velocity will have significantly more kinetic energy, so any impact will be more destructive; the kinetic energy is determined by the square of the velocity meaning small a small increase in velocity results in a large increase in energy. So, on the road, it’s really all about energy because the velocity attainable (relative to what’s going to be hit) means any increase in mass is going to be negligible. However, were a car to be travelling at close to the speed of light the relativistic mass greatly would be increased, further contributing to the energy of the crash and making things worse still.
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