Table of Mechanics Demonstration

List of Mechanics Equipment & Supplies

Lecture Demonstrations

Loop the Loop, 1M40.20

Topic and Concept:

Location:

LoopTheLoop01-400.jpg

Abstract:

A ball is placed at various initial heights and allowed to roll down an incline and around a loop, assuming the ball has enough energy.

Equipment

Location

ID Number

Loop the Loop

ME, Bay T7

Hard Nylon Ball

ME, Bay A2, Shelf #2

Important Setup Notes:

Setup and Procedure:

  1. Orientate the loop the loop on the table so the audience can see the ball roll around the track.
  2. A 1 1/2" hard nylon ball is placed on the track at it lowest point for the instructor to use.
  3. Place the ball at varying heights on the longer ramp and then release.
  4. A meter stick maybe useful.

Cautions, Warnings, or Safety Concerns:

Discussion:

When the ball is brought up to some point on the track, it is given gravitational potential energy m*g*h where m is the ball's mass, g is the acceleration due to gravity, and h is the height relative to the bottom of the loop. Throughout the demonstration, this quantity will be the total energy of the ball, it it will remain constant as per the conservation of energy, neglecting friction. The force that "compels" the ball to turn in a loop is the normal force of the track on the ball. That is to say the centripetal force is provided by the normal force. [ N = m * v2/ R ] Where N is the normal force, v the speed of the ball, and R the radius of the loop. Using this information, it is then possible to calculate a minimum speed for the ball to have at the top of the loop without falling or slipping off the track. Subsequently, a minimum initial height can be calculated, neglecting friction. As it turns out, this critical height is hcrit = (5/2) * R

See the references below for a detailed calculation of the minimum height necessary for which the ball can fall freely and make it around the loop.

This is also the basic building blocks for amusement rides and roller-coasters.

LoopTheLoop03-250.jpg

LoopTheLoop04-250.jpg

LoopTheLoop05-250.jpg

LoopTheLoop06-250.jpg

Videos:

References:

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