We saw in Example 5.6 how a centrifuge can be used to separate cells from a liquid. To increase the rate at which objects can be separated from solution, it is useful to make the centrifuge’s speed as large as possible. If you want to design a centrifuge of diameter 1.5 m to have a force of 100,000 times the force of the Earth’s gravity, what is the speed of the outer edge of the centrifuge? Such a device is called an ultra centrifuge. Centrifuges of this type are currently being used by certain countries (including Iran) to produce what is called enriched uranium for use in nuclear power plants or weapons. Naturally occurring uranium contains two isotopes (which have slightly different masses), only one of which is useful in these applications (see Chapter 30). Ultra centrifuges like the one considered in this problem are used to process the gas UF₆ and thereby separate the two uranium isotopes.