Passage III

When viewed from above, the path of a launched object is expected to be a straight line. However, because Earth rotates, the Coriolis effect causes the object to be deflected, either to the right of the expected path in the Northern Hemisphere, or to the left of the expected path in the Southern Hemisphere. The magnitude of deflection (MOD) is a distance that serves as a measure of the Coriolis effect (see Figure 1). The MOD is the same when measured at the same latitude (for example, 30°) in either hemisphere.

Students conducted 3 experiments to study the Coriolis effect.

Experiment 1

The students performed 5 trials, each at a different latitude. In each trial, they launched a ball due east at a speed of 25 m/s over a distance of 100 m. They then measured the ball’s MOD, in cm (see Table 1).

Experiment 2

The students performed 5 trials, each at 45°N latitude. In each trial, they launched a ball due east at a different speed over a distance of 100 m. They then measured the ball’s MOD (see Table 2).

Experiment 3

The students performed 5 trials, each at a different latitude. In each trial, they repeatedly launched 2 identical

disks, each 4 cm in diameter, directly toward one another at identical speeds across a 200 m long frictionless horizontal plane. The speed was adjusted for each launch until the students had determined the minimum launch speed required for the disks to just avoid colliding (see Figure 2). Table 3 shows their results.