Oscillators, Frequency, and Time Period

Oscillator Fundamentals

  • Oscillation: A back-and-forth or up-and-down motion occurring around a central point known as the equilibrium position.
  • Amplitude: The maximum displacement from the equilibrium position to the maximum distance traveled. Amplitude does not affect the time period.
  • Full Oscillation (Full Cycle): A complete motion starting from a specific point (usually an extreme), moving to the opposite side, and returning to the same starting point.

Time Period and Frequency Formulas

  • Time Period (TT): The time taken for one complete oscillation.
  • Basic Equation: T=tnT = \frac{t}{n}, where tt is time and nn is the number of oscillations.
  • Mass Spring System: Calculated as T=2πmkT = 2\pi\sqrt{\frac{m}{k}}, where mm is mass and kk is the spring constant.
  • Simple Pendulum: Calculated as T=2πLgT = 2\pi\sqrt{\frac{L}{g}}, where LL is the length of the rope and gg is gravity (9.8m/s29.8\,m/s^2).
  • Frequency (ff): The reciprocal of the time period, f=1Tf = \frac{1}{T} or f=ntf = \frac{n}{t}.
  • Angular Frequency (ω\omega): Described as ω=2πT\omega = \frac{2\pi}{T} or ω=2π×f\omega = 2\pi \times f.

Kinematics Graphs of Oscillations

  • Displacement vs. Time: Produces a sine wave or sinusoidal graph as the object moves between positive and negative maximums.
  • Velocity vs. Time: Represented by a cosine graph.     - Maximum Velocity: Occurs when the object passes through the equilibrium position.     - Zero Velocity: Occurs at the extremes (maximum displacement) where the object momentarily stops.
  • Acceleration vs. Displacement: A straight line sloping downwards.     - When displacement is negative maximum, acceleration is positive.     - When displacement is positive maximum, acceleration is negative.

Questions & Discussion

  • Question: "Can you explain the velocity time graph one more time?"
  • Response: At the equilibrium point (t=0t = 0), velocity is at its maximum. As the oscillator reaches the maximum compression/extension point (extreme), it stops for a millisecond, resulting in zero velocity. On the return through the midline, velocity is maximum in the opposite direction.
  • Question: "In radians or… Because of the pi?"
  • Response: The context of the calculation (T=2πmkT = 2\pi\sqrt{\frac{m}{k}}) isn't an angle, so the unit of the calculator doesn't change the result, though the formula uses radians components.
  • Question: "Is it hard?"
  • Response: The instructor noted the work on the pendulum calculation (T=2πLgT = 2\pi\sqrt{\frac{L}{g}}) results in 0.170.17 for length when solving for a specific period.
  • Discussion on units: The unit for frequency is analyzed as Hz\text{Hz}. A calculation result given was 1.2s1.2\,s for the time period and approximately 7.547.54 for angular frequency (ω\omega).