chapter 14 notes vibrations and waves. section 14.1 objectives use hooke’s law to calculate the...
TRANSCRIPT
Section 14.1 Objectives
• Use Hooke’s law to calculate the force exerted by a spring.
• Calculate potential energy of an elastic spring.
• Identify objects in simple harmonic motion.
• Determine variables that affect the period of a pendulum.
• Describe the affect of resonance on an object.
Example ProblemA spring stretches by 18 cm when a bag of potatoes weighing 56 N is suspended from its end.
a. Determine the spring constant. b. How much elastic potential energy is
stored in the spring when it is stretched this far?
Example Problem
How long must a pendulum be on the Moon, where g=1.6 m/s2, to have a period of 2.0 s?
Section 14.2 Objectives
• Differentiate between transverse and longitudinal waves.
• Determine wave speed, wavelength, and frequency using corresponding equations.
Example Problem
A sound wave has a frequency of 192 Hz and travels the length of a football field, 91.4 m, in 0.271 s.
a) What is the speed of the wave?b) What is the wavelength of the wave?c) What is the period of the wave?d) If the frequency was changed to 442
Hz, what would be the new wavelength and period?
Section 14.3 Objectives
• Relate a wave’s speed to the medium in which the wave travels.
• Describe the motion of a wave as it encounters boundaries.
• Apply the principle of superposition to wave interference.
Waves at Boundaries
• Free boundary– http://www.physicsclassroom.com/mme
dia/waves/free.cfm
• Fixed boundary– http://www.physicsclassroom.com/mme
dia/waves/fix.cfm
Superposition of Waves
• Interference– Constructive– Destructive
• http://www.physicsclassroom.com/Class/waves/U10L3c.cfm