Wednesday, 24 April 2013

Distances travelled by a hard drive

Once in a while I'll come up with strange ideas and one of them was the curious thought I had about distances covered by hard drives.

The diameter of the platter in a standard PC hard drive is 8.89 cm and as a result its circumference will be 27.96 cm. The typical hard drive today spins at give or take 7200 revolutions per minute, which works out to 120 per second. Since we know the distance travelled every minute, we can work this out to 120.82 KM/h, which is 10.82 KM/h faster than the speed limit on the Coquihalla Highway.

This means a hard drive could in theory keep up with highway traffic.

Let's assume that we don't have to worry about powering the hard drive because we know that otherwise it won't work, but where could the hard drive possibly go should it have access to some unique power source and it could keep itself upright and use its platter as a wheel?

The distance between the capital of British Columbia, Victoria to its island neighbour, Nanaimo is approximately 110 KM, which means the hard drive could easily drive down the highway and get there in less than an hour. However, the speed limit in the Malahat section is 80 KM/h, so it would likely get a speeding ticket for having done so. We'll ignore this consequence since the hard drive doesn't have a licence anyway.

How about a larger feat? Perhaps we want to drive from Vancouver to Toronto? Well, thanks to the hard drive's enormous stored energy, it could travel the shortest distance of 4,373 KM in just around 36 hours. But this is cutting through the United States, so if we were to stay within our own borders, it would work out to about the same as it would be 4,389 KM but would have the consequence of speeding through city streets which are set with a maximum 60 KM/h. The hard drive would be quite the rebel.

Okay. So we have this fancy energy source and as a result could go anywhere. How about to outer space? What if the hard drive managed to manipulate its gyroscopic forces to defeat gravity and fly upwards to places beyond our atmosphere? Since we're already breaking the laws of the road, we can go for broke and completely break the laws of physics.

In this Time article, it's stated that the average car's age is 11 years old and has gone a distance of 165,000 miles (266,000 KM). The distance between the Earth and the Moon is 384,400 KM, so the average car has yet to make it as far. How long would it take for the hard drive to get to our celestial neighbour? It would take about 132 days for it to reach its destination--for reference, the astronauts that visited there took almost four days to arrive.

Since cars are averaging 11-years on the road, how much further does the hard drive go in that time? It would be approximately 11,649,963 kilometres. The hard drive would take half-a-century at best to reach Mars when it is at its closest, but considering the closest that planet will be to us will be about 58,000,000 KM in 2018, it's unlikely that it would get there in time and would probably take a whole century if it were to leave now as the distances can reach around 100,000,000.

This is all presuming that the hard drive just doesn't give out before it gets there. These devices are quite amazing and have the ability to outlast expectation and sometimes just flat out die. My rule of thumb is that a hard drive is only good for up to 5-years of continuous operation, which means it would die out long before it made it to our planetary neighbour.

Closing on this, a 10,000 RPM hard drive is only going at 160 KM/h so while it would get to Mars a tad faster, it's not really an improvement.

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