ROTATIONAL MOTION
Lab Report #6
April 25, 2019
ENGR/PHYS 216 - Section 216
Team 2Abstract
In this experiment, the center of mass of various shapes was determined using the vertical lines technique.
Then the center
...
ROTATIONAL MOTION
Lab Report #6
April 25, 2019
ENGR/PHYS 216 - Section 216
Team 2Abstract
In this experiment, the center of mass of various shapes was determined using the vertical lines technique.
Then the center of mass was proven by verifying its motion was rotating around the center of mass. In the
second part of this lab, conservation of angular momentum was tested by placing a weight on a spinning
mass. This information was also used to find the moment of inertia for each shape as well.
1. Introduction
In this lab, students were required to find the center mass and moment of inertia of differently shaped
wooden boards. The center of masses were found using the vertical lines technique and then verified by
tracking the rotation of the object. Then, conservation of angular momentum was proven by dropping a
weight on the spinning object and calculating the final angular momentum. Finally, the moment of inertia
of another board was calculated using the fact that angular momentum was conserved. Jetson software
was used to collect and store data from a camera, which measured vectors of position, velocity, and
acceleration.
2. Purpose
The purpose of this experiment was to determine the center of mass of several boards, as well as their
moment of inertias for each shape and prove that angular momentum was conserved. The team was
commissioned by PELA to test whether or not angular momentum was going to be conserved on the new
planet.
3. Background
The lab involved several basic physics principles. The first of which was the conservation of angular
momentum. Due to the absence of external torque, it can be assumed that angular momentum is
conserved. Therefore, we applied the following equation:
To prove conservation of angular momentum on the fixed L shape, the equation above was applied to the
conditions and formulated the following equation. If angular momentum is conserved, both sides of the
equation should be (reasonably) equal.
To solve for the inertia for the fixed pentagon shape, the same formula was applied for conservation of
angular momentum. However, in this case the equation was used specifically to solve for the unknown
inertia of shape, as follows:
4. Experimental Setup and Procedure
The center of mass was found by the vertical lines method. As shown in Figures 1-8, a small, 20 g mass
was tied to the end of a string. The end of the string with no mass attached was tied to a screw and
inserted into one of the holes in the boards. The center of mass was found by allowing the mass to drop.
The board was then rotated until the string was perpendicular to the ground. Lines were drew on the board
Team 2
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