# Oscillation of Torsional Pendulum

Topics: Measurement, Harmonic oscillator, Simple harmonic motion Pages: 11 (3107 words) Published: February 4, 2013
DEPARTMENT OF MECHANICAL ENGINEERING ALL Sections must be completed using Block Capitals or typed CODE AND TITLE OF COURSEWORK Course code: MECH1008 Title: OSCILLATION OF A TORSIONAL PENDULUM

STUDENT NAME: CHEW KOK HAO, DANIEL

DEGREE AND YEAR: MENG IN MECHANICAL ENGINEERING

LAB GROUP: 1

DATE OF LAB. SESSION: 03 OCT 2011

DATE COURSEWORK DUE FOR SUBMISSION: 10 OCT 2011

ACTUAL DATE OF SUBMISSION: 09 OCT 2011

LECTURERS NAME: Dr. PAUL FROMME

PERSONAL TUTORS NAME: Dr. A R GREIG

I confirm that this is all my own work (if submitted electronically, submission will be taken as confirmation that this is your own work, and will also act as student signature)

Signed: via moodle

University College London, Torrington Place LONDON WC1E 7JE

CONTENTS
PAGE No. 1. Introduction......................................................... 2 1.1. Objectives................................................... 1.2. Background................................................. 2. Experimental Procedure...................................... 2.1. Apparatus.................................................... 2.2. Procedure.................................................... 3. Results................................................................. 2 2 2 2 2 3

3.1. Processing of Data....................................... 3 3.2. Analysis of Results....................................... 4 3.3. Error Analysis............................................... 6 4. Discussion of Results........................................... 7

4.1. Comparison with Theory............................... 7 4.2. Discussion.................................................... 8 5. Conclusions.......................................................... 8 6. References........................................................... 9

1

1.

Introduction
1.1. Objectives To investigate the harmonic motion of a torsional pendulum upon angular deflection. 1.2. Background In a torsional pendulum, a disc shaped mass is suspended from a thin wire. Angular deflection about the axis of the wire was introduced to the disc. When released, the torsion moment of the wire will attempt to untwist itself, causing the disc to oscillate back and forth around the wire axis, creating a harmonic motion. This experiment will determine the relation between the magnitude of angular deflection and the resultant harmonic motion by measuring the period T of oscillation on various angular deflection. The second part of the experiment will investigate the relation between the mass of the pendulum disc and the resultant harmonic motion by measuring the period T of oscillation on different disc mass. The last part of the experiment involves the introduction of a damping medium, in the form of an oil bath, and thereafter determining the effects of damping.

2.

Experimental Procedure
2.1. Apparatus The torsional pendulum set-up consist of a pendulum disc, suspended from a thin steel wire that is fixed to the end of a support structure. An open top circular container containing an oil bath, is mounted directly below the suspending disc. The oil bath can be raised to enclose the pendulum disc by the means of a lever. The measurement equipment used are namely the angular scale on the disc (read off a pointer), a steel ruler measuring to 1mm,a digital vernier caliper measuring to 0.01mm and a digital micrometer screw gauge measuring to 0.001mm. A digital stopwatch was used for time measurement, recording up to 0.01seconds. 2.2. Procedure Before the start of the experiment, measurements were done on the Torsional Pendulum to obtain the length of the pendulum wire (L), diameter of pendulum disc (dw) and radius of pendulum disc (R). All dimensions were measured in millimeters. The basis of the experiment involves twisting of the pendulum disc to a predetermined angle (θ), and thereafter releasing it to allow the disc to untwist itself. The...