6.1.5 Displacement-Time Graph

Oscillation

1. Waves are formed by a series of oscillation.
2. In order to understand waves, we must understand oscillation.

Technical Terms Related to Oscillation

1. An equilibrium position is a point where an oscillating object experiences zero resultant forces.
2. A complete oscillation occurs when the vibrating object:
   1. moves to and fro from its original position and
   2. moves in the same direction as its original motion.
      
      
      
      
      
      
3. Amplitude is the maximum amplitude of an object from its equilibrium position. The SI unit for amplitude is meter, m.
   
   
   
   
   
   
4. The greater the amplitude, the greater the mechanical energy possessed by the oscillating system.
5. Period is defined as the time required for one complete oscillation or vibration .
6. Frequency, f is the number of oscillation that take place in one second. The SI unit for frequency is Herz (Hz).
7. Frequency can be related to period by the following equation
   
   f = frequency
   T = Period
   
   

1. The displacement of the oscillating object at any time.
2. The amplitude
3. The period.

Example:

Figure above shows a displacement versus time graph for a vibrating object.
a. Find the amplitude, period and frequency for the vibrating system.
b. What is the displacement of the object at t = 0.3 s,
c. Sketch in the same axis above, a graph of a wave which the frequency and amplitude are half of the wave in the figure above.

Answer:
a.
The amplitude, A = 10cm
The period, T = 0.4s
The frequency,

b. The displacement at 0.3s = -10cm

c.

Comparing Displacement-Time Graph and Displacement- Distance Graph

（Displacement-time graph - Graph of oscillation)

(Displacement-distance graph - Graph of Waves)

1. Both the displacement-time graph and the displacement distance graph looked similar. However they are 2 different types of graph.
2. The displacement-time graph illustrate the displacement of an object over time whereas the displacement-distance graph tell the position of the vibrating particles of a wave.
3. For a displacement- distance graph, the distance between 2 crest/trough represent the period whereas for the displacement-distance graph, it represents the wavelength.