# Rotational Inertia of Disk and Ring.docx - Rotational...

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Rotational Inertia of Disk and RingSara Khalaf Yasmeen Rizik Sydni StarlingHortencia RuizSection: Physics 222.08Date: 11/28/2017
Abstract The goal of this experiment is to find the rotational inertia of a ring; a vector quantity we take in physics. The rotational inertial found is of an object that is shaped as a ring and a disk. Our aim is to measure the angular acceleration produced by a constant torque. The angular acceleration is used to measure the to find a ring. The aim of finding and measuring these quantities is develop critical thinking and physics skills in analyzing results and making comparisons like comparing the inertial values to theoretical values as part of our analysis to come to a conclusion. The Primary concepts explored thus is the relationship of newtons laws with the rotational inertia. Circular motion and gravity and mechanics are also concepts explored. Another objective that should be achieved in this lab experiment is dealing with uncertainties andsystematic and random errors. We learned how to use previous concepts learned in physics like newton laws, angular speed and angular acceleration to relate to rotational inertia to be able to solve for unknown values, create relationships between quantities and enhance our understanding.The apparatus used for this experiment is shown in figure3 and figure4 found under the procedure section. Figure3 demonstrates the rotary motion sensor. The apparatus includes a a disk, a support rod, a string, a mass hanger and a mass. figure4 it shows how we setup the mas ring with the disk. Other Electric and Non-electric equipment used throughout this experiment is mentioned and discussed in more details in the procedure section.TheoryThe rotation inertia is also referred to as moment of inertia or angular inertia but we’ll be using the term rotational inertia throughout this lab report. The rotation inertia of arigid bodyis atensorthat determines thetorqueneeded for a desiredangular accelerationabout a rotational axis. The mathematical definition of rotational inertia is the ratio between the net angular momentum L of a system to its angular velocity ω. This forms into the following equation I=Lωshowing that the rotational Inertia is inversely proportional to ω and directly proportional to the angular momentum. Thus from this equation the independent quantity (The rotational inertia) depends on the values of the angular momentum and angular velocity. For a ring in this case, The rotational inertia of the ring about its center of mass is given by:IR=12M(R12+R22)…………………………………………………………………(1)Where:M: is the mass of the ring were using in this experimentin kg.
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