# Terminal Velocity – even for Electric Cars

Tom Cruise has one of these. It’s a Bugatti Veyron Super Sport, one of the fastest production cars in the world this year. It could go even quicker but the speed has been limited because the tyres won’t be able to handle it if it goes faster.

A newer contender is the Hennessy  Venom which outstrips the Bugatti and actually costs less. The Koenigsegg Agera RS is faster still, at 277mph, but, wait – the big news next year will be that Elon Musk’s Roadster will outstrip them all – an electric car able to do 0-60 in a blistering 1.9s and an as yet unannounced top speed.

Q: Why do cars have a top speed?

A: When the forward thrust of the engine is balanced by the resistive force of air pushing back against it, all forces are in equilibrium and so there’s no change in speed.

Have you noticed, a 300bhp sports car can go faster than a 300bhp tractor, since the air slides over the sports car more efficiently so it can go faster before the air resistance is as large as that experienced by the tractor.

When a parachutist opens his chute, his weight is quickly balanced by the push of air under the canopy, so he falls at a steady speed. We recall that weight is a force. Unbalanced forces change a body’s state of motion (speed it up or slow it down. Here’s the textbook stuff.

An object falling vertically has two forces acting on it-weight acting downwards and air resistance acting upwards. At the beginning of its fall, travelling slowly, weight is larger than air resistance, so it accelerates downwards.

As speed increases, weight stays the same but air resistance increases, so the net force and consequent acceleration decreases.

When air resistance and weight are the same, net force is zero and the body falls at a steady speed. (AS students – Newton 1) This is called TERMINAL VELOCITY.

We’ve all seen modern parachutes – this image is of a da Vinci parachute which he invented in the 16th century. A Swiss man made one recently and actually used it on a 3000m drop. EEK!

Now download terminal-velocity-2and try a terminal velocity experiment yourself. My son showed me this when he went to University. I was surprised – perhaps you will be too.

## 6 thoughts on “Terminal Velocity – even for Electric Cars”

1. Christopher Norman says:

Actually sir the fastest production now is the SSC Ultimate Areo TT at 256mph (412kmh). But hey, whose counting.

Chris

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2. esfscience says:

You’re absolutely right, Christopher. The post has been modified accordingly. Hope you like the picture!

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Never heard of this Car. It was the Dodge hennessey viper the fastet car in the world and has a top speed of 255mph.
Anyways nice notes.

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4. Ali Salhe says:

You’re absolutely right the SSC Ultimate Areo TT is the fastest car but i thought that the bugatti Veyron was the fastest but it is the 2nd fastest car

Bugatti Veyron: 253 mph+, 0-60 in 2.5 secs. Aluminum, Narrow Angle W16 Engine with 1001 hp, base price is \$1,444,000. With the highest price tag, no wonder this is rank #2.

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5. Right Now, the fastest Production car is the Bugatti Veyron. Bugatti Automobiles SAS had been in a similar situation when their existing customers asked the company to not only design their second model optically differently but also to create a version with a sportier and more extreme driving experience. The result is a car with a uniquely high performance of 882 kW (1.200 bhp ) With a maximum torque of 1.500 Newton metres and a limited top speed of 415 km/h which is 257.87 Miles/hour (mph) (to protect the tyres).
Bassem Saleh

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6. John Vagabond says:

Oops. Info outdated.I will update asap.

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