Experiment 19, Modified:  When two objects moving along a common straight line collide and maintain motion along the same line as before collision, the total of their momenta immediately after collision is equal to the total immediately before collision.

By setting up head-on collisions of various spherical objects and allowing them immediately after collision to fall a known distance under the influence of gravity, we can from the horizontal ranges of their falls determine their velocities immediately after collision.  If one object is stationary prior to collision, and if the velocity of the other immediately before collision is determined, we can then compare total momentum before collision to total momentum after.  This comparison constitutes a test of the Law of Conservation of Momentum for two objects.

See CD EPS01 for Lab Kit Experiment 19.  Note that the setup here has been adapted somewhat from the version on the video clip; however the differences and similarities should be easy to understand.

In this experiment we will allow the larger marble in the kit to roll from rest down the binding indentation of a hardcover book inclined at an angle, then onto the binding indentation of another book lying flat on a horizontal tabletop.   This setup replaces the curved-end incline seen in the video clips.  The setup of the books is shown in the figure below. 

Note that the binding indentation in recent printings of the book might not be deep enough to keep the marble 'in the groove'.  If this is the case for your book you can make the following adaptation:

 

The setup is illustrated below:

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The setup with creased strips of paper:

End view of book with creased paper and marble:

The marble, referred to hereafter as the 'ball', will roll down the two books and strike another marble (also called a ball) head-on, after which both balls will fall as projectiles to the floor. We will obtain data to determine the velocities of the balls after impact and the velocity of the first ball before impact, from which we can make various tests of the conservation of momentum.

You will collide two balls of unequal mass, with the larger ball rolling down the incline and the smaller set up as a stationary target.

Using the program MOMSIM (available on the 164.106.222.236 homepage under Simulations), analyze the first collision from a variety of reference frames.

Analyze the collision from the center-of-mass frame, using various coefficients of restitution.

Analysis of errors