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## Coriolis and Centrifugal Acceleration: Instructor's Guide

### Main Ideas

Determining the direction of the Coriolis and centrifugal accelerations in various situations.

### Students' Task

*Estimated Time: 10 minutes, including wrap-up*

- Determine the direction of the Coriolis acceleration, $-2\Vec\Omega\times{\Vec v}_R$.
- Determine the direction of the centrifugal acceleration, $-\Vec\Omega\times(\Vec\Omega\times\Vec r)$.

### Prerequisite Knowledge

- The expression for acceleration in a rotating frame, namely:

$${\Vec a}_R = {\Vec a} - 2\,\Vec\Omega\times{\Vec v}_R - \Vec\Omega\times(\Vec\Omega\times\Vec r)$$

### Props/Equipment

- Small whiteboards with markers

### Activity: Wrap-up

Remind students how to manipulate their right hand in order to determine the direction of the cross product. Use this to determine the orientation of the Coriolis acceleration, relative to the direction of motion (to the right). Then demonstrate that the double cross product in the centrifugal acceleration leads to a reversal of the direction, so that the centrifugal acceleration points radially outward.

### Extensions

Is there a modified version of Newton's Second Law which holds in a rotating reference frame?