Untitled Document

Physics Demo Number: 112

Approximate

Run Time: 10 min

Demo Description

The photo shows a Loop-the-Loop apparatus hanging on its home hook on the left back wall, opposite [H-5-3]. Balls for the apparatus are in Kit(112) on [H-4-5].

Scientific Principles

Particles can traverse vertical circles if they have the proper central forces available to them .

Equipment

Loop-the-Loop Apparatus Constructed from Bent Aluminum Channel
Balls to Roll on Apparatus around a Vertical Circle.

Equipment Location

On left back wall hook (opposite [H-5-3]).
Kit (112) on [H-4-5].

Instructions

The dedicated apparatus is of course for showing a ball dynamically traversing a vertical circle.

The aluminum channel, forming the loops and entrance and exit ramps , serves to let the ball roll with minor frictional losses and to provide the requisite central forces needed in successfully negotiating the desired path.

One should however carefully note that the rolling motion of the ball must be considered in any attempt to calculate how far up the higher ramp the ball must be started for a successful circuit of the path with no free fall parabola involved.

This is in marked contrast to one's ability to ignore the rolling motion of the balls in [005] for a successful full explanation of that demonstration.

If the purpose of doing the demonstration is simply to provide proof of concept of a loop-the-loop, then one needs only to experimentally determine a release point on the high side that will pull the motion off properly and gloss over the rolling of the sphere and its effect on the whole motion.

In the last mentioned case, be prepared to respond to an astute observer noticing that the release point is higher than common sense might predict for it, and have an explanation in mind.