Lagrangian Points

in particular, with respect to the Earth and Moon, the locations where the gravitational forces are equal and so objects positioned at such points remain fixed. There are five such points between the Earth and Moon.

Taken from Dictionary of Science

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The Lagrangian points (pronounced /ləˈgrandʒiən/; also Lagrange points, L-points, or libration points), are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects (such as a satellite with respect to the Earth and Moon). The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to rotate with them. They are analogous to geostationary orbits in that they allow an object to be in a "fixed" position in space rather than an orbit in which its relative position changes continuously.

More technically and precisely, Lagrangian points are the stationary solutions of the circular restricted three-body problem. For example, given two massive bodies in circular orbits around their common center of mass, there are five positions in space where a third body, of comparatively negligible mass, could be placed which would then maintain its position relative to the two massive bodies. As seen in a rotating reference frame with the same period as the two co-orbiting bodies, the gravitational fields of two massive bodies combined with the centrifugal force are in balance at the Lagrangian points, allowing the third body to be stationary with respect to the first two bodies.

Taken from Wikipedia

Ultracentrifuge

a special centrifuge machine that generates high centrifugal forces as it is capable of spinning at speeds up to 50,000 revolutions per minute. The ultracentrifuge is most commonly used during the separation of the various ORGANELLES within cells. The larger and more dense organelles will form a deposit in the centrifuge tube more readily than the smaller, less dense ones. The nucleus is the largest organelle of any normal cell and will be deposited at the bottom of a centrifuge tube when the ultracentrifuge spins at a force of 600g for 10 minutes, whereas the smaller MITOCHONDRION needs a higher speed of 15,000 g for 5 minutes to be deposited.

Taken from Dictionary of Science