Transcript Document

Week 7
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Periodic Motion
Week 7
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What’s the oscillation period of the radio signal
from 107.7 “The End”? (f=107.7MHz)
Week 7
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What’s the oscillation period of the radio signal
from 107.7 “The End”? (f=107.7MHz)
Is the oscillation period of 96.5 “Jack FM” larger or
smaller than this?
Week 7
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Week 7
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The ultrasonic transducer in a medical ultrasound
imaging device is a very thin disk (m=0.10 g) driven back
and forth in SHM at 1.0 MHz by an electromagnetic coil.
The maximum restoring force that can be applied to the
disk without breaking it is 40,000 N.
• What is the maximum oscillation amplitude that won’t
rupture the disk?
• What is the disk’s maximum speed at this amplitude?
Week 7
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Vision is blurred if the head is vibrated at 29 Hz
because the vibrations are resonant with the
natural frequency of the eyeball held by the
musculature in its socket. If the mass of the
eyeball is 7.5 g, what is the effective spring
constant of the musculature attached to the
eyeball?
QuickTime™ and a
TIFF (Uncompressed) decompressor
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Week 7
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Spiders detect vibrations of their spring-like web to
determine what’s been caught. Suppose a 13.0 mg fly
lands in the center of a horizontal spider's web,
causing the web to sag by 3.40 mm. When the fly gets
stuck, the web will sag until the spring force balances
the fly’s weight.
• What is the spring
constant of the web?
• Modeling the motion of
the fly on the web as a
mass on a spring, at what
frequency will the web
vibrate when the fly hits it?
Week 7
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LAB 7 OBJECTIVES:
• To investigate the relationships between position,
velocity, acceleration and restoring force for periodic
motion.
• To investigate the basic properties of periodic motion—
period, frequency and amplitude—and the relationships
between them.
• To understand the interplay between potential and
kinetic energy in periodic motion.
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An oxygen molecule (O2) can be modeled as two masses
connected by a spring-like bond. An oxygen molecule can
vibrate at many different frequencies but the smallest
frequency vibration it can have is 5x1013 Hz. Graph the
distance between the atoms and the kinetic, potential and
total energy of the molecule versus time.
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Week 7
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