Nothing Special   »   [go: up one dir, main page]

Simple Harmonic Motion Ph202/Note01/17.02.2009

Download as pdf or txt
Download as pdf or txt
You are on page 1of 2

1

SIMPLE HARMONIC MOTION

PH202/Note01/17.02.2009

Definition
A particle is said to execute a simple harmonic motion about a fixed point if it experiences a force
which is always directed toward the fixed point and the magnitude of the force is proportional to the
magnitude of displacement from the fixed point.

O: fixed point; : displacement of the particle from the fixed point; : simple harmonic force
From the definition,
=

If the simple harmonic motion is along the x-axis,


= .
The differential equation of simple harmonic motion along the x-axis is given by:
2

2 + = 0, m being the mass of the particle.


2

Or 2 + 2 = 0, 2 = , : angular frequency of shm


The solution to this equation is of the form:
= sin + = cos +
A: amplitude; : angular frequency; : initial phase .

= /2

The Geometrical Definition of Simple Harmonic Motion

Q: reference point which moves on the circle with angular speed .


Physical Significance of
Let T: the time period of shm.
To show that =

Let us look at the reference circle. At t=t the reference point Q is shown on the circle. The particle P
will complete one oscillation when the point Q completes one rotation. Since the point Q has an
angular speed , it will complete one rotation in 2/ seconds.
So T=2/.
Or =

/ .

The phase of the motion


The displacement and velocity of a particle at time t is completely determined by the quantity
(t+). This quantity is called the phase of the motion.

You might also like