In the figure at the right is shown three graphs of the shapes of the same taut
ID: 1472112 • Letter: I
Question
In the figure at the right is shown three graphs of the shapes of the same taut elastic string in three different circumstances, labelled A, B, and C. In some of the problems below, the string represents a guitar string, tied down at both ends, while in others, it is part of a very long telephone wire whose ends are not shown. Be careful to note which is which for each problem! The string is light enough that the effects of gravity can be ignored. In each case, the bit of string at the position x = 23 cm is painted blue.
1. Suppose the three graphs all represent the same string, tied down at x = 0 and x = 70 cm, and at the same tension. What can you say about the three frequencies of oscillation?
A. Situation A has the highest frequency.
B. Situation C has the highest frequency.
C. You cant say anything from the information given.
D. The three frequencies are all the same.
E. Situation B has the highest frequency.
2. Suppose the three graphs all represent the same string, tied down at x = 0 and x = 70 cm, but their tensions have been adjusted so that all three situations are all oscillating at the same frequency. What can you say about the tensions in the three cases?
A. The tension is string A is the greatest.
B. You cant adjust the tensions to make the frequencies the same since the wavelengths are different.
C. The tension in string C is the greatest.
D. All three tensions are the same.
E. You cant say anything from the information given.
3. Suppose that graph C represents the string, tied down at x = 0 and x = 70 cm, under tension. What can you say about the acceleration of the blue bead in case C at the instant shown?
A. It is upward.
B. It is 0.
C. It is downward.
D. You cant say anything from the information given.
4. Suppose that graph C represents part of a long wire, under tension, and is showing a left traveling wave at a particular instant. What can you say about the velocity of the blue bead in case C at the instant shown?
A. It is downward.
B. You cant say anything from the information given.
C. It is 0.
D. It is upward.
5. Suppose that graph C represents part of a long wire, under tension, and is showing a left traveling wave at a particular instant. What can you say about the acceleration of the blue bead in case C at the instant shown?
A. It is downward.
B. You cant say anything from the information given.
C. It is 0.
D. It is upward.
In the figure at the right is shown three graphs of the shapes of the same taut elastic string in three different circumstances, labelled A, B, and C. In some of the problems below, the string represents a guitar string, tied down at both ends, while in others, it is part of a very long telephone wire whose ends are not shown. Be careful to note which is which for each problem! The string is light enough that the effects of gravity can be ignored. In each case, the bit of string at the position x = 23 cm is painted blue.
1. Suppose the three graphs all represent the same string, tied down at x = 0 and x = 70 cm, and at the same tension. What can you say about the three frequencies of oscillation?
A. Situation A has the highest frequency.
B. Situation C has the highest frequency.
C. You cant say anything from the information given.
D. The three frequencies are all the same.
E. Situation B has the highest frequency.
Explanation / Answer
a) situation A is fundamental mode of vibration while situation B and C are secon and third harmonic, so frequency of situation c is higher frequency.
b) if frequency, length and linear density are same for three graphs then the tensions are also directly proportional. So tension in the sitation c is greater than other two.
c) Acceleration of a vibrating object would always oppose the displacement. this mean that accleation always oppose the position. In situtation c the bead is at equilibrium and direction is not specified so we cannot specify the acceleration.
d) At the equilibrium position, the velocity is at maximum. The velocity of the particle coming from the extreme position to the equilibrium is increaseing so the direction is positve upward.
e) When the wave is travelling to the left the position of the particle would be upward so acceleration should be in downward direction.