Please explain why these answers are correct A transverse periodic wave is estab

Question

Please explain why these answers are correct
A transverse periodic wave is established on a string. The wave is described by the expression 0.005 with a speed of 20.0 m/s, what is its frequency f? B) 0.64 Hz If the wave travel D) 63.7 H E) 400 Hz Ans: D Difficulty: Medium Section Def: Section 16-4 Problem 6 44. A train moving at a constant speed is passing a stationary observer on a platnorm. On one of the train cars, a flute player is continually playing the note known as concert AV- 440 Hz). After the flute has passed, the observer hears the sound with a frequency of 415 Hz. What is the speed of the train? The speed of sound in air is 343 m/s. 7.3 m/s B) 12 m/s C) 21 m/s D) 37 m/s E) 42 m/s Ans: C Difficulty: Medium SectionDef: Section 16-9 Problem 7 A charge q -6.0 uC is ved m horizontally to point P in a region where an field mor electric 0.25 the electric potential energy of is 250 V/m directed vertically, as shown. What is the change in the charge? A) -2.4 x 10 SJ

Explanation / Answer

5)2pi/lamda=20

lamda=0.1pi=0.314m

v=f*lamda

f=v/lamda=63.7Hz

6)f=f0*(v/(v+vs))

415=440*(343/(343+vs))

vs=20.67m/s=21m/s

7)On moving a charge perpendicular to a field, the change in potential energy is 0.

8)Since the sound is exactly out of phase, if the path difference is lamda/2, we will hear a constructive interference.

Let the distance from A be x.

Path difference=(2-x)-x=lamda/2

lamda=v/f=343/680=0.5044m

2-2x=0.5044/2

x=0.874m=0.88m

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