Newton's Cradle
This video demonstrates some of the principles behind Newton's Cradle, a common desktop toy. ( Newton's Cradle ).
This excellent discussion http://www.lhup.edu/~dsimanek/scenario/cradle.htm explains the physical principles behind Newton's cradle. This is however a great deomstration of the conservation of energy and momentum. The following lab exercise approaches require a Newton's Cradle apparatus. Many fancy versions can be purchased, however any nice setup will work for this.
Experiment 1
Setup:
Using a standard Newton's Cradle apparatus and two simple equations determine the behavior of Newton's Cradle.
Assumptions:
All Ball's have equal mass (m). All collisions are perfectly elastic. Energy and momentum will be conserved.
Experiment 1:
Pull and release one ball. Note the results and explain mathematically in terms of conservation of engergy and momentum.
m1v1 = m2v2
1/2 m1 v12 = 1/2 m2 v22
Record observed behavior.
Discussion:
Do the results meet your expectations?
Experiment 2:
Predict possible behavior if 2 balls are raised and released. Before performing experiment document possible behavior and determine if this behavior will meet both the laws of conservation of momentum and energy. Perform the experiment.
Discussion:
Do the results match the prediction? Is this the only possible result? Are there possibly physical principles that are important here.
Experiment 3:
Attempt different combinations, including dropping balls simulatenously from both ends of the device. Discuss and mathematically prove results.
Further Discussion:
In this apparatus all balls have the same weight and composition. What would occur if this was not the case?
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