# Images from laboratory four

## 13 September 2007

Renee releases a single marble into a line of marbles while investigating the effect of momentum qualitatively.

A line-up of five marbles in part one of the laboratory.

One in, one out.

Note that the collision also results in some movement of the "line" marbles. There are considerations of angular momentum that may be the principal explanation for this behavior. The colliding marble has spin and thus angular momentum. Where linear momentum of the marble is p = mv, the angular momentum L = Iω where I = 0.4mrČ and ω = v/r. Thus the angular momentum of a colliding marble is L = 0.4mrv. This is conjectured to have the effect of the colliding marble continuing to "push" on the marble line after the initial collision as the colliding marble "spins down" rapidly. Of course the ejected marble has to "spin up" rapidly, and the loss of linear momentum seen in later sections of this laboratory are thought to be due in large part to "spinning up" the ejected marble. Reducing or minimizing external torque by lubricating the track may help reduce these spin effects which at present make the core concepts of inertia and the conservation of linear momentum less obvious.

Tulpe-Louisa gets ready to time a marble in the taw-duck collision. Michelle has released the taw.

As Garry makes calculations, Mellyanna and Maverick look on.

Physci fall 2007 •
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