# 1D50.52 - Central Forces - Centripetal Force - 1 to 4 mass ratio

Code Number:
1D50.52
Demo Title:
Central Forces - Centripetal Force - 1 to 4 mass ratio
Condition:
Good
Principle:
1 to 4 masses, Forces Due To Circular Motion
Area of Study:
Mechanics
Equipment:
Pasco Centripetal Force App., Weight set, 1 to 4 masses for the Pasco unit.
Procedure:

Video Credit: Jonathan M. Sullivan-Wood

The masses that have the 1 to 4 ratio are the brass mass at 105 grams and the steel mass at 420 grams.  Put the 105 gram mass on the Pasco apparatus and show that a 100 grams weight can make the mass hang straight down in line with the indicator on the unit.  Now rotate the unit until you find the rotation rate that makes the mass again hang straight down according to the indicator.  This rotation rate can be recorded with the interface.  Now do the same operations with the 420 gram mass and again record the rotation rate with the interface.  These two plots can be displayed simultaneously to show that the rotation rates are in a ratio of 1 to 2.

The brass mass has attachments that can take it to 210 grams, or double it's starting mass.  This gives your an intermediate mass and rotation rate if you want to plot the curve.

References:
• Alzira Stein-Barana, Deisy P. Munhoz, Douglas A. Galbiatti, Cristiane S. Leme, "Uniform Circular Motion: Playing with Mini Wind-Up Trains", TPT, Vol. 48, # 7, p. 487.

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