# Demo Detail

Table Cloth Pull

Purpose:
To demonstrate the inertia of the objects

Equipment:
Tablecloth and apron Silverware and plastic plate, bowl, and cup Weighted pop tarts box and soup can

Equipment Location:
Other

Procedure:
First put on the apron as that is part of this demonstration. Now lay the tablecloth on the table but do not allow it to cover the other side of the table. Place the objects that are available on top of the tablecloth and make sure there is not too much slack in the part of the tablecloth on the table. Now take the part of the tablecloth that is hanging off the table in front of you. Let there be a lot of slack in the table cloth so that when you pull the table cloth it will be at it's greatest speed when it starts to be pulled out from under the objects. The objects should stay in relatively the same places on the table.

Hints:
When you pull the tablecloth you need to remember to pull straight out away from the table because if you pull up or down it will move the objects. Also this demonstration can be done with and without water inside of the plastic cup it is up to you, if you are really worried about the water you can place a weight in the cup.

Relevant derivations/explanations:
There are four forces that act upon the objects in this experiment at some point in the demonstration. The forces are gravity, the normal force of the table, the friction of the silk tablecloth and the friction of the table. When you first start pulling on the tablecloth the forces at that point are gravity, the normal force, and friction with the tablecloth. At that time the forces cause the objects to start to move in the direction of the tablecloth. Once the tablecloth has been pulled from under the objects the forces acting on them are gravity, the normal force of the table and friction from the table. The fricition cause by the table is in the opposite direction then the friction of the tablecloth so the table friction slows the objects.