Chapter 7

Rotational Motion, Conservation, Gravity Review

Hans Christiaan Huygens

Demos to Prepare:

Rotational Inertia:
String & Mass.
Bubble in TT.
Donald's Snow Ball Gattling Gun..
Spin & shrink.
Mass on string.
Carousel.
Gyroscopes, Gimbaled & Bicycle.

When released from orbit, we take off tangentially, Video:

Trying for Critical Velocity in a Swing. The RamSwing Video:

The Vomit Comet Video:

Demos:

String & Mass.
Bubble in TT.
Donald's Snow Ball Gattling Gun.
Spin & shrink.
Mass on string.
Carousel
Gyroscopes, Gimbaled & Bicycle.

On the carousel, rotational momentum is conserved as the riders move inward to the center. The carousel speeds up because the riders' inertia tries to keep them going at the same number of meters per second that they had on the outer ring. The more riders the better because their mass must compete with the mass of the merry-go round. The carousel may double its revolutions per second!

Airplane on a Conveyor, Relative Motion

Let's say a small airplane needs to reach 80 km per hour on a runway to achieve enough lift to take off.  Imagine that we now place the plane on a huge conveyor belt as long as the runway.  Just as the plane revs it's engine up and releases it's brakes for takeoff, we start spinning the conveyor in the opposite direction at 80 km per hour. Can it take off?

Trying it out, video:

An overnight photograph at the North or South Pole shows that the stars form circles
around the Pole Star (Polaris over the North Pole). Ah, the Earth is rotating beneath
the stars.

Angular Displacement

Angular Speed

Angular Acceleration

Centripetal Acceleraton

The Acceleration of Gravity is 9.8 meters/sec2, Video:

Sample Gravity Problem

When released from orbit, we take off tangentially, Video:

Here Endeth Chapter 7