Transcript Simple Harmonic Motion

Simple Harmonic Motion (SHM)
• SHM: is periodic motion about an equilibrium
point where the restoring force is proportional to
the distance from equilibrium
– Periodic motion: Repeated motion
– Equilibrium position: Position where object will
come to rest. Fnet = 0
Amplitude
Amplitude: maximum displacement from
equilibrium
– Relates to the amount of energy
– Unit: meters
Simple Harmonic Motion
ex: pendulum (at small angles) and mass
on a spring
At equilibrium
• Velocity is at a maximum
• Net force is zero
At maximum amplitude
• Velocity is zero
• Net force is at a maximum
When would the acceleration be
zero? When would it be a maximum?
Why will the mass
eventually stop?
Friction
What can you tell me about the:
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•
•
•
Force at B?
Velocity at B?
Acceleration at A?
Speed at C?
2 Truths and a Lie
With a partner
1. Write down 2
2. Write down 2
truths and 1 lie
truths and 1 lie
about the velocity
about the force of
of an object in
an object in
simple harmonic
simple harmonic
motion.
motion.
You must use the words equilibrium and
maximum amplitude in your statements.
Period & Frequency
• Period (T): time it takes to complete one cycle
– Unit: seconds
• Frequency (f): number of cycles or vibrations
per unit of time
– Unit: 1/sec = Hertz (Hz)
1
T
f
1
f 
T
Practice Problem
An angry bird flaps its wings every 1.2
seconds. What is the period and frequency
of the wings’ motion?
SHM and Waves
• Simple Harmonic Motion- Pendulum
Waves