Circular Motion
Forces and Motion

You spin me right round

Stories from Physics for 11-14 14-16 IOP RESOURCES


Ultracentrifuges are devices used to separate materials and can achieve accelerations of up to 1,000,000 times the acceleration due to gravity and speeds of 150,000 rpm. The first human centrifuge was designed by Erasmus Darwin, Charles Darwin’s grandfather, who was interested in the origin of vertigo.He labelled his device a ‘rotative couch’. Darwin’s friend, James Watt, drew up detailed blueprints for the apparatus but the device was never built. NASA researchers found that fish tolerate the effects of high acceleration surprisingly well and hypothesised that immersion in water might have a similar protective effect on humans. Hence the researchers built an aluminium capsule, named the iron maiden, large enough to contain a human, that could be filled with water and attached to a centrifuge. The iron maiden was tested on R. Flanagan Gray, a physician at the Jonsville Laboratory. Flanagan Gray stayed alert for 25 seconds while spinning, reaching a peak acceleration of 32 g and setting a new endurance record. He reported suffering only mild sinus pain during the trial.As humans can tolerate small accelerations reasonably well, engineers have suggested that spacecraft might reduce travel time by moving with a constant low value of acceleration rather than an initial high acceleration followed by a long period of constant velocity. To test this claim, centrifuge-training officer Carl Clark volunteered to spend 24 hours in a centrifuge experiencing 2 g acceleration. The gondola of the centrifuge was fitted with a reclining chair and a small electric stove so Clark could cook and eat while being accelerated. Clark managed to work, eat and sleep during the experiment and reported the only side effect of the experience was mild fatigue.


Circular Motion
can be analysed using the quantity Centripetal Acceleration
can be described by the relation F=m(v^2)/R
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