Uniform Rotation of Frames 57Direction of Motion
North
South
East
WestDeflection of trajectory
East
West
South
North- For motion in the Southern Hemisphere
Direction of Motion
North
South
East
WestDeflection of trajectory
West
East
North
SouthEXERCISE 2.1.10.B Verify the above properties of the Coriolis force. Hint:
The particular shape of the trajectory does not matter; all you need is the direction
ofr\, similar to Exercise 2.1.9.
EXERCISE 2.1.11. A Because of the Coriolis force, an object dropped down
from a high building does not fall along a straight vertical line and lands to
the side. Disregarding the air resistance, compute the direction and mag-
nitude of this deviation for an object dropped from the top of the Empire
State Building (or from another tall structure of your choice).
One of the most famous illustrations of the Coriolis force is the Fou-
CAULT PENDULUM, named after its creator, the French scientist JEAN
BERNARD LEON FOUCAULT (1819-1869). Foucault was looking for an
easy demonstration of the Earth's rotation around its axis, and around
1850 came up with the idea of a pendulum. He started with a small weight
on a 6 feet long wire in his cellar, and gradually increased both the weight
and the length of the wire. He also found a better location to conduct his
experiment. The culmination was the year 1851, when he built a pendulum
consisting of a 67 meter-long wire and a 28 kg weight swinging through a
three-meter arc. The other end of the wire was attached to the dome of the
Paris Pantheon and kept swinging via a special mechanism to compensate
for the air resistance and to allow the swing in any vertical plane. Because
of the rotation of the Earth around its axis, the Coriolis force was turning
the plane of the swing by about 270 degrees every 24 hours, in the clockwise
direction as seen from above.
EXERCISE 2.\.Yl.c Draw a picture and convince yourself that, if the pen-