help

The Coriolis Effect on a Cannon Ball Fired from the North Pole

-- | June 8, 2014

Question: High above the north pole, firing a cannonball in the eastern direction confers a velocity in the eastern direction and there is no north, no south, and no west direction given to the cannonball by the cannon.
Gravity pulls on the eastern traveling cannonball in the radial direction towards the center of the earth. When the orbiting cannonball reaches the equator, the velocities are in the eastern direction from the original firing of the cannonball and in the western direction from gravity, but there is no velocity in the south direction. How then does the cannonball continue to travel south? — Hector

Answer: I think that the effect you are trying to describe in this example is the “Coriolis Effect“. The Coriolis Effect produces a deflection of the path of an object within a rotating coordinate system. Note that this path deflection is not real, as it only appears to happen because the coordinate system that establishes a frame of reference for the observer is also rotating. Your cannon ball firing example is a classic example of the Coriolis Effect. To rephrase your experiment, if a cannon ball is fired from the North Pole at a target toward the equator, the cannon ball will land to the right of its true path because the target area has moved farther to the east during the cannon ball’s travel. There are several other examples of this effect described in the link above if you are interested.

Jeff Mangum

The National Radio Astronomy Observatory is a facility of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
	Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.
	The U.S. National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."
	AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.