Notes from Toppers

1. Oscillatory Motion:

Definition: Oscillatory motion is a periodic motion where the body moves to and fro about a fixed point, called the mean position.

Characteristics:

  • Oscillatory motion repeats itself at regular intervals.
  • The body’s displacement from the mean position is a sinusoidal function of time.
  • The body’s velocity and acceleration are also sinusoidal functions of time.
  • The period of oscillation is the time taken for one complete oscillation.
  • Frequency of oscillation is the number of oscillations per unit time.

Reference: NCERT Physics Part 1, Chapter 15, Oscillations.


2. Displacement, Velocity, and Acceleration in SHM:

Equations:

  • $$Displacement, x=A\sin\omega t$$
  • $$Velocity, v=A\omega \cos \omega t$$
  • $$Acceleration, a=-A\omega^2 \sin\omega t$$ where,
  • (A) is the amplitude of oscillation.
  • (\omega) is the angular frequency of oscillation.

Graphical Representation:

(Displacement) vs. (Time) graph: [Image of a sine curve]

(Velocity versus Time) graph: [Image of a cosine curve]

(Acceleration) vs. (Time) graph: [Image of a sine curve, shifted down by (\pi/2)]

Phase and Phase Difference:

  • The phase of an oscillation is the fraction of the way through a complete oscillation that has occurred.
  • The phase difference between two oscillations is the difference in their phases.

Reference: NCERT Physics Part 1, Chapter 15, Oscillations.


3. Period, Frequency, and Amplitude in SHM:

Definitions:

  • Period (T) is the time taken for one complete oscillation.
  • Frequency (f) is the number of oscillations per second.
  • Amplitude (A) is the maximum displacement from the mean position.

Relationship:

  • $$f=\frac{1}{T}$$
  • (\omega=2\pi f) where (\omega) is the angular frequency.

Reference: NCERT Physics Part 1, Chapter 15, Oscillations.


4. Energy in SHM:

Total Energy: In SHM, the total energy is the sum of kinetic energy and potential energy:

$$E=K+U=\frac{1}{2}kA^2\cos^2\omega t+\frac{1}{2}kA^2\sin^2\omega t=\frac{1}{2}kA^2$$

  • where (k) is the spring constant.

Conservation of Energy: The total energy of a system in SHM remains constant.

Reference: NCERT Physics Part 1, Chapter 15, Oscillations.


5. Applications of SHM:

  • Springs: Springs oscillate when stretched or compressed. The period of oscillation of a spring is given by $$T=2\pi\sqrt{\frac{m}{k}}$$
  • Pendulums: A pendulum is a weight suspended from a pivot point. The period of oscillation of a pendulum is given by $$T=2\pi\sqrt{\frac{l}{g}}$$ where (l) is the length of the pendulum and (g) is the acceleration due to gravity.
  • Oscillating Masses: Masses attached to springs or suspended from pivots can oscillate. The period of oscillation depends on the mass and the spring constant or length of the pendulum.
  • Measuring Instruments: SHM is used in various measuring instruments, such as accelerometers and seismometers.