# Rotation

Videos shown here contain grids, rulers, frame counters and other overlays that allow students to make measurements directly from the videos. Students can use this data to answer questions and solve problems. For each video, sample questions are shown, and in some cases, sample lesson plan ideas.

#### Rotating Fish Tank

This clip shows a fish tank filled with water rotating at about one rotation per second. The surface of the water forms a paraboliod – a 3-dimensional parabolic surface. In the second part, fish are placed in the tank to observe the effect of the rotation.The fish were unharmed by this demonstration.

Sample question: Can you derive the equation for the parabola that passes through the axis of rotation of the tank? Does the shape shown in the video match your derived equation?

#### Bicycle Wheel Gyroscope

This clip shows a student sitting on a platform that can rotate freely while holding a weighted bicycle wheel that is rotating. When the student flips the bicycle wheel over, the he begins to rotate.

View the Quicktime file: Direct Measurement Video of a Bicycle Wheel Gyroscope (Quicktime Video 7.1MB Jul15 13) here.

Download the Quicktime file: Direct Measurement Video of a Bicycle Wheel Gyroscope (Quicktime Video 7.1MB Jul15 13) here.

Sample question: What is the ratio of the rotational inertia of the bicycle wheel around its axle to the rotational inertia of the entire system around the axle of the platform?

#### Sliding and Rolling Ball

This clip shows a pendulum colliding with a billiard ball. The billiard ball slides and rolls along a horizontal track.

View the QuickTime file: Video of a sliding and rolling ball (Quicktime Video 5.1MB Apr29 13) here.

Download the QuickTime file: Video of a sliding and rolling ball (Quicktime Video 5.1MB Apr29 13) here.

Sample question: What is the coefficient of friction between the ball and the track surface?

Sample activity: Rolling and Sliding Ball

#### Marble Collides with Block

This clip shows a marble fired from a pneumatic cannon colliding with a wood block. The block moves horizontally and rotates.

View the QuickTime file: Marble collides with wood block (Quicktime Video 7.8MB Feb8 13) here.

Download the QuickTime file: Marble collides with wood block (Quicktime Video 7.8MB Feb8 13) here.

Sample question: Is linear momentum conserved?

Sample question: Is angular momentum conserved?

Sample activity: Conservation of Linear and Angular Momentum During a Collision

#### Disk accelerated by rocket motor

Screen shot from a video of disk accelerated by rocket motor (Quicktime Video 733kB Jul9 12)
This clip shows a plywood disk being accelerated by a small model rocket motor mounted at the rim.

View the QuickTime file: video of disk accelerated by rocket motor (Quicktime Video 733kB Jul9 12) here.

Download the QuickTime file: video of disk accelerated by rocket motor (Quicktime Video 733kB Jul9 12) here.

Sample question: Determine the average force provided by the rocket motor during the first two revolutions.

#### Bicycle wheel accelerated by weight

Screen shot from a video clip of wheel accelerated by falling weight (Quicktime Video 1.4MB Jun4 12)
This clip shows a bicycle wheel being accelerated by a small metal cylinder suspended by a string wrapped around the rim.

View the QuickTime file: video clip of wheel accelerated by falling weight (Quicktime Video 1.4MB Jun4 12) here.

Download the QuickTime file: video clip of wheel accelerated by falling weight (Quicktime Video 1.4MB Jun4 12) here.

Sample question: Determine the rotational inertia of the bike wheel.