1. Vocabulary (Due Tue 3/20):
Today’s HW & Agenda
Vocabulary (Due Tue 3/20):
Ch. 12 Vocabulary part 1
Wavelength
Amplitude
Period
Frequency
Transverse
Longitudinal
Medium
Crest
Trough
Node
antinode
Review Ch. 8 & 9 Exam
Review Ch. 12 Reading HW8
Simple Harmonic Motion Activity
Lecture Hooke’s Law, Mass-Spring Systems, & Pendulums
HW9: 12A p.441 # 1, 2, Sect Rev p.445 #1, 2, B p. 449 #1, 2, 3,
First 5 vocabulary Terms
Textbook Chapter 12

2. periodic motion & Waves video

3. Simple Harmonic Motion Activity Partner 1 Pulls the Paper at CONSTANT Velocity Partner 2 Traces Bob’s Motion with Pencil

4. Simple Harmonic Motion Activity Look at the Drawing. Do the Following:
Measure the Wavelength, . Label it.
Measure the Amplitude, A. Label it.
Label the crest and the trough
Label the nodes
Time 3 full periods of your pendulum (use watch or cell phone) , then divide that time by 3 to find the period, T. Record.
Calculate the frequency, f (f=1/T).
Write your names on the paper & turn in.

5. Periodic Motion A spring-mass system (also known as a mass-spring system) at equlibrium compressed stretched
Spring Masses
horizontal
x
x

6. Periodic Motion
All three diagrams show a snapshot in time of a moving mass on a spring
compressed at
equilibrium
stretched
PEe = ½ k(x) k = spring constant (N/m)
units: Joules x = displacement from equilibrium position
Spring Masses
vertical
Elastic Potential Energy
x x
x x

7. Conservation of Energy
Vocabulary:
spring masses
Conservation of Energy
Kinetic Energy:
KE = ½ mv2
Hooke’s Law
Force:
F = -k(x)
Periodic Motion Oscillate – to move back and forth in a periodic motion As the mass attached to the spring oscillates, ENERGY is TRANSFORMED from Potential to Kinetic to Potential. F = max  PEe = max KE = 0 F = 0 PEe = 0 KE = max F = max
x
inertia keeps the mass moving
x

8. Conservation of Energy
Vocabulary:
spring masses
Conservation of Energy
Kinetic Energy:
KE = ½ mv2
Hooke’s Law
Force:
F = -k(x)
Periodic Motion
Which Direction will the mass move next?
F = max 
PEe = max
KE = 0
F = 0
PEe = 0
KE = max
F = max
x
x

9. Period T Kinetic Energy: KE = ½ mv2 Force: F = -k(x)
spring masses
Period T
Kinetic Energy:
KE = ½ mv2
Force:
F = -k(x)
Periodic Motion Period, T, is the time (seconds) for 1 complete oscillation
x
x

10. pendulums L (meters) Period g = 9.8 m/s2 T
Periodic Motion Period, T, is the time (seconds) for 1 complete oscillation
L (meters)
g = 9.8 m/s2

11. moving at equilibrium position
pendulums
Periodic Motion
All three diagrams show a snapshot in time of a moving pendulum bob
hmax v=0
PEg = max
KE = 0
hmax v=0
PEg = max
KE =0
h0 v=max
PEg = KE = max
moving at equilibrium position

12. END OF LECTURE