# Rotating Frames of Reference

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## Summary

This video leads students through descriptions of the motion of two objects observed from two frames of reference: a rotating turntable, and the relatively stationary ground frame. The centripetal and Coriolis accelerations that arise in rotating frames of reference are explored. Finally, we use the Coriolis effect to explain the rotational direction of hurricanes in the Northern Hemisphere.

## Learning Objectives

After watching this video students will be able to:

• Explain why centripetal and Coriolis accelerations arise in rotating frames of reference.
• Apply their understanding of the Coriolis acceleration to determine the direction of rotation of hurricanes.

Funding provided by the Singapore University of Technology and Design (SUTD)

Developed by the Teaching and Learning Laboratory (TLL) at MIT for SUTD

## Related Resources

Instructor Guide

Rotating Frames of Reference Instructor Guide (PDF)

It is highly recommended that the video is paused when prompted so that students are able to attempt the activities on their own and then check their solutions against the video.

During the video, students will:

• Determine whether or not a force opposite an applied tension force on a disk on a rotating turntable exists, and where it comes from.
• Determine the velocity of the disk in the ground frame, given that it is not moving in the turntable frame.
• Compute a general formula that finds the acceleration of an object in one frame in terms of the acceleration in another, given that one frame is rotating but not translating with respect to the other.
• Apply the formula to determine the accelerations of objects in two different examples.
• Discuss why the observed motion of a rolled ball is curved in a rotating frame of reference.
• Predict the motion of a rolled ball as observed from the ground frame.
• Use the Coriolis effect to explain why hurricanes in the Northern hemisphere rotate counterclockwise.

### Subtitle

• English - US (SRT)