Examples of systems that execute SHM • The one-dimensional projection of uniform circular motion.
• A mass oscillating up and down on a spring.
• A floating object bobbing up and down in still water.
• A simple pendulum oscillating through a small angle.
cm 0
y A x
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
8..08.0
• A compass coming to rest in North–South direction.
• Each prong of a tuning fork when it is struck.
• The rise and fall of the tide, i.e. high tide to low tide over a 12-hour period.
• A molecule vibrating inside a solid. S
Fig 7.1:Various examples of simple harmonic motion
Terms Used to Describe SHM AMPLITUDE
Amplitude (A) is the maximum distance that an object moves from its equilibrium position.
It is a scalar quantity with an SI unit of metre (m).
When a spring is compressed or stretched past its natural length then allowed to oscillate with SHM, the difference between the natural length and the actual length (that it was set at before being allowed to oscillate) is equal to the amplitude of oscillation.
FREQUENCY
Frequency (f ) is the number of cycles (or oscillations) the object completes per unit time.
It is a scalar quantity with an SI unit of hertz (Hz).
f time taken no. of oscillations
1 Hz is the frequency when 1 cycle is completed per second. 1 Hz 1 cycle s1PERIOD
