7. If wavelength of third harmonic of standing waves in a sting is Sm, what is the length of the sting? Ch. 16 Problems ( 1. A guitar is tuned when the tension in its strings is adjusted. Should you increase or detrease the tension in a sering to produce a higher-frequency 8. A piano tuner simultaneously strikes a 262 Hz tuning fork and the widdle C key on a piano and hears beats with a heat perind of 0.500 s. What are the passible frequencies of the slightly out-of-ture key? Should the tension in the piano wire be changed In such a way as to shorten or to lengthen the perind of te heats? Sound? 2. A cork floating on a lake bobs up and down as a small wave pacses. The cork completes 4.00 cycles in 1.00 s. The wave peaks are 10.0 cm apat. Find the speed of the wave 3. A wave traveling in the positive x-dinction has a frequracy of 25.0 Hz, as in Figure P13.37. Find the (a) amplitude, (b) wavelength, () perind, and (d) speed of the wave. 9. A pipe closed at ane of its ends has a length of 0.8m. What is the distance between a node and adjacent anti-node of its second hanmonic. 10. The longest pipe in a certain organ is 4.00 m long. What is the lowet frequeny the oegan will produe it the pipe is (a) open a huth vnds, (b) closed al nne nd? 10 cm 4. A 1.00 m long string of mass 0.0100 kg, under a Dension cf 100 N, transmits wmve of smplitude 2.00 cm and wavelengh 10.0 m. (a) Find the spenl of the wave form. b) How tar does a pacticle of the string travel during one cycle? (c) What is the average speed af a particle of the string? In the amangement shown, an object can be hung from a string (with linear mass density =0.002 00 kg/m) that passes over a light pulley. The string is connected to a vihrator (of constant Erequency . and the length of the string between point Pand the pulley is L.- 2.00 m. When the mass mof the object is either 160 kg or 25.0 kg, sanding waves are oberved, however, no slnding waves are observed with any mes between these values. (a) What is the fequency of the vibrator? (h) What is the largest object mass for which standing waves could be observed? 5. Extra (might be on test- don't hand in) 11. It a long rope is hung from a ceiling and waves Are sent up the rope from its lower end, they do not asCend with constan: speed. Explain. 12. An aliplane mechanic notices that the sound Emm a twin engine aireraft rapidly varies in loudness when both engines are nunning could be causing this variation frum loud to seofr What 13. If one end of a heavy rope is attached to one end of a light rope, the sperd of a wave will change as the wave goes from the heavy rupe to the light one. Wil the speed increase or decrease? Whax happens to the frequency? To the wavelength? Vhrator 14. Find the speed of sound in mercury, which has a bulk modulus uf appnuximately 2.80 x 10" Nim nd a density of 13 600 kgm. 6. A sound wource muves through alr towanl a stationary therver. The fequrney of the sound the observer hean is 20.0% higher than the source fiequeney. lew fast is the source moving? 15. A GU.OO-cm guitar string under a tension of 50.000 N has a mass per unit length of 0.100 00 g/cm. What is the highest resonant frequency that can be heud by a person capable of hearing frequencies up to 20 000 He?