Simple Harmonic Motion (SHM) Equations
What is simple harmonic motion?
- A particle undergoing simple harmonic motion moves along a straight line subject to the following constraints:
- The acceleration of the particle is always directed towards a fixed point on the line of motion
- The acceleration is proportional to the displacement of the particle from the fixed point
- As a result the particle oscillates back and forth along the line around the fixed point
- Many physical systems can be modelled using simple harmonic motion
- One example is an object attached to a spring oscillating in one dimension, when friction, air resistance and other such resistive forces are disregarded
What is the equation that describes simple harmonic motion?
- The standard form of the simple harmonic motion equation is
- x is the displacement of the particle from the fixed point
- The fixed point is normally indicated by O and is the origin (i.e. zero point) of the coordinate system
- The fixed point O is known as the centre of oscillation
- is the constant of proportionality, and represents the strength of the force accelerating the particle back towards point O
- The negative sign means that the acceleration is always directed back towards O
- We use to assure that the constant is positive, and also to simplify the notation for the solution to the equation
- is the acceleration of the particle
- With simple harmonic motion, Newton’s ‘dot notation’ is often used for the derivatives
- In this notation, and