Physics I, Lab 3:

Fall 2005

General instructions

1. Please work in groups of two or three.
2. Please write up a short response/answer for each of the exercises.
3. Please hand in only one write-up per group.

Two-Dimensional Momentum Conservation

Consider the multiflash photograph of a collision of two billiard balls. Assume that the time interval between flashes is .1 second. Do the measurements below reasonably carefully.

1. Choose a coordinate system. (A clever choice will make the problem a little easier.)
2. Determine the velocity vectors for each of the balls before and after the collision. Write the vector in component form.
3. Determine the momentum of the system before and after the collision. Write your answer in component form.
4. Is momentum conserved?

Estimation

1. Estimate the amount of tea currently in China.
2. If the land of the earth were divided up equally, what area of land would each person get?

Dimensional Analysis

1. The period T of a simple pendulum depends on the length L of the pendulum and the strength of earth's gravitational field g. Find a simple combination of L and g that has the dimensions of time.
2. Check the dependence of the period T on the length L by measuring the period for three different values of L. (The period T is defined as the time for a complete to-and-fro swing.)
3. The correct formula involves a numerical factor that is dimensionless and hence can't be obtained by dimensional analysis. Using your data from the above question, estimate the value of the numerical factor.