Chapter 5: Oscillations Flashcards
Define free oscillation
An object oscillates at its natural frequency
Give 3 examples of free oscillations
- Vibrations of a guitar string when you pluck it 2. Vibrations of a tuning fork when you strike it 3. Oscillation of a child in a swing
Define oscillation
An object moves back and forth repeatedly on either side of its equilibrium position
Define displacement
The distance an object has moved from its equilibrium position
Define amplitude
Maximum displacement of an object from its equilibrium position
Define period
The time for one complete oscillation (one side to the other and back again)
Define frequency
Number of oscillations per unit time
Define angular frequency
The rate of change of angle in radians per second = 2pi x frequency
Define phase difference
The fraction of an oscillation between the vibrations of two oscillating systems expressed in radians or degrees
3 requirements for SHM
- Mass that oscillates 2. Equilibrium position 3. Restoring force that returns the mass to its equilibrium position
Explain why period of an object with SHM is independent of amplitude
- If you plot a graph of a=-(2pif)^2x it is a straight line with -ve gradient of (2pif)^2 through the origin 2. The gradient of the graph is independent of the amplitude 3. Therefore frequency also independent so the oscillator keeps steady time
Describe and draw the graph for the change of displacement in SHM
Sine curve starting at: a) (0,0) if beginning at equilibrium position b) (0,A) if starting at amplitude Max. displacement = amplitude
Describe and draw the graph for the change of velocity in SHM
-Velocity = rate of change of displacement -So graph = grad. of x/t graph -Phase diff. of 90 degrees w. x/t graph
Describe and draw the graph for the change of acceleration in SHM
-Acceleration is rate of change of velocity -So graph = gradient of v/t graph -a=-kx so it is also a reflection of x/t graph in x axis
Describe and explain the interchange between k.e. and p.e. in SHM
-Total energy is constant for an undamped system -k.e. max. at equilibrium position -p.e. max. at amplitude -Energy changes between k.e. and p.e.