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(Motion & Kinematics)

Simple harmonic motion basics

Simple Harmonic Motion Basics

What is Simple Harmonic Motion (SHM)?

Simple Harmonic Motion (SHM) is a type of periodic motion where an object moves back and forth over the same path. It is characterized by its sinusoidal oscillation, meaning it moves in a smooth, wave-like pattern.

Some examples of SHM include:

  • A pendulum swinging back and forth.
  • A mass attached to a spring oscillating up and down.
  • Vibrations of a tuning fork.

Key Characteristics of SHM

  • Restoring Force: The force that brings the object back to its equilibrium position is directly proportional to the displacement and acts in the opposite direction. This is given by Hooke's Law: F=kxF = -kx, where kk is the spring constant and xx is the displacement.
  • Equilibrium Position: The central point around which the object oscillates.
  • Amplitude: The maximum displacement from the equilibrium position.
  • Period (T)(T): The time taken to complete one full cycle of motion.
  • Frequency (f)(f): The number of cycles per second, given by f=1Tf = \frac{1}{T}.

Mathematical Representation of SHM

The motion of an object in SHM can be described using the following equations:

  • Displacement: x(t)=Acos(ωt+ϕ)x(t) = A \cos(\omega t + \phi)
  • Velocity: v(t)=Aωsin(ωt+ϕ)v(t) = -A\omega \sin(\omega t + \phi)
  • Acceleration: a(t)=Aω2cos(ωt+ϕ)a(t) = -A\omega^2 \cos(\omega t + \phi)

Where:

  • AA is the amplitude.
  • ω\omega is the angular frequency, calculated as ω=2πf\omega = 2\pi f.
  • ϕ\phi is the phase angle, determining the starting position of the motion.

Worked Example

Calculate the period and frequency of a pendulum with a length of 1 meter. Assume g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Tuity Tip

Hover me!

Tuity Tip: Remember that in SHM, the acceleration is always directed towards the equilibrium position, making it a restoring force.

Visualize: Drawing a diagram of the motion can help you understand the direction of forces and motion.

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