Presentation on theme: "Lecture 11 Getting down to business….. Last Time We covered the topic of Energy Bolemon – Chapter 6 Problems to try: pg 123 1,2,3 (use energy), 5,9,15,16."— Presentation transcript:
Lecture 11 Getting down to business…..
Last Time We covered the topic of Energy Bolemon – Chapter 6 Problems to try: pg 123 1,2,3 (use energy), 5,9,15,16 Energy is conserved. The energy when a process starts is the same as the total energy at the end but it could change into various forms. Springs have potential energy ((1/2)kx 2 when they are extended or compressed. We demonstrated that the string on a guitar behaves like a spring.
During Oscillation (Important for Music)
Conclusions The bigger the mass the lower the frequency. The bigger the spring constant (stiffer) the higher frequency.
The Tones f0f0
Take a close look at what the string is actually doing: STANDING WAVES NODE NODE
A Flash “Photograph” “NODE”
What is a “node”??? A point where nothing changes with time. The fixed end of the string is a node There are associated nodes with standing waves.
A Closer Look FIXED BY HARDWARE ROCKING POINT
How does the thing work? STANDING WAVES WWhat i ii is standing? WWhat i ii is a wave?
DEMO -01 Let’s do the wave.
Demo -02 The rope to the back of the room.
What was traveling along the rope?? The rope didn’t go anywhere. Segments of the rope moved up and down. This up and down motion means that each little piece of the rope has kinetic energy.
The pulse moves with a speed v.
Another look at the pulse Rope not moving anywhere
Closer Look Lots of Kinetic Energy Here
Time goes by … Energy Energy
What happens at the other end?
Not fixed at the end???
Guitar String CONSTRAINTS The string is tight. The two ends are FIXED. They are always NODES.