CHAPTER 15
Periodic Motion
, 15.1
Periodic Motion & Energy
, 15.1 Summary
• Periodic motion - repeats itself at regular time intervals.
Oscillation (or vibration) is back-and-forth periodic motion.
• The period T is min. time interval in which periodic motion repeats,
and amplitude A of the motion is the mag. of the max. displacement
of moving object from its equilibrium position.
• Simple harmonic motion - periodic motion in which the
displacement of a system from its equilibrium position varies
sinusoidally with time. Such a system is called a simple harmonic
oscillator.
• Frequency f of periodic motion is the number of cycles per second
and is defined as
1
f º .
T
1 Hz º 1 s-1.
, 15.1 Summary
• Periodic motion → continuous conversion between PE & KE
• Equ. of motion for object relates its acceleration to ∑ 𝐹
Unstretched
Compressed Equilibrium Stretched
F → pos. ∑ F = 𝟎. F ← neg.
aMax → pos. a =0 aMax ← neg.
v=0 v = max v=0
PE = max PE = 0 PE = max
KE = 0 KE = max KE = 0
Periodic Motion
, 15.1
Periodic Motion & Energy
, 15.1 Summary
• Periodic motion - repeats itself at regular time intervals.
Oscillation (or vibration) is back-and-forth periodic motion.
• The period T is min. time interval in which periodic motion repeats,
and amplitude A of the motion is the mag. of the max. displacement
of moving object from its equilibrium position.
• Simple harmonic motion - periodic motion in which the
displacement of a system from its equilibrium position varies
sinusoidally with time. Such a system is called a simple harmonic
oscillator.
• Frequency f of periodic motion is the number of cycles per second
and is defined as
1
f º .
T
1 Hz º 1 s-1.
, 15.1 Summary
• Periodic motion → continuous conversion between PE & KE
• Equ. of motion for object relates its acceleration to ∑ 𝐹
Unstretched
Compressed Equilibrium Stretched
F → pos. ∑ F = 𝟎. F ← neg.
aMax → pos. a =0 aMax ← neg.
v=0 v = max v=0
PE = max PE = 0 PE = max
KE = 0 KE = max KE = 0
