# physics

posted by .

A string is tied across the opening of a deep well, at a height 5 m above the water level. The string has length 7.51m and linear density 4.17 g/m; any time there is a wind, the string vibrates like mad. The speed of sound in air is 343 m/s. Assuming that the resonance causing this vibration involves the lowest harmonics of both the string and the well, calculate the string's tension. Answer in units of N.

• physics -

Match the fundamental lowest frequency of the string (string wave speed divided by twice the string length) to that of the well acoustic fundamental (treated as an open pipe) and solve for the tension, which will be the only unknown.

• physics -

The well is a quarter wavelength long, compute frequency.

THen, knowing freq, mass density you can find tension from the law of strings.

• physics -

A half wavelength actually, node both ends, antinode in the middle.

• physics -

Oh, yes, the well is a quarter wave.

• physics -

To elaborate on Prof Damons last remark: The water at the bottom provides a 180degree phase change, so the path up and down have to add to the other 180 degrees needed for wave reinforcement, thus 1/4 lambda length down, and 1/4 lambda up.

## Similar Questions

1. ### physics

A light string has its ends tied to two walls separated by a distance equal to five-eighths the length of the string. A 53 kg mass is suspended from the center of the string, applying a tension in the string. What is the tension in …
2. ### physics

A light string has its ends tied to two walls separated by a distance equal to five-eighths the length of the string. A 53 kg mass is suspended from the center of the string, applying a tension in the string. What is the tension in …
3. ### physics

a framed picture of weight 15N is hung on a wall, using a piece of string. The ends of the string are tied to two points, 0.60 m apart on the same horizontal level, on the back of the picture.Find the tension in the string if the string …
4. ### Physics

Plus 10 for each correct response and no penalty for incorrect answers. The length of a string is 996 cm. It is held fixed at each end. The string vibrates in six sections; i.e., the string has six antinodes, and the string vibrates …
5. ### Physics

The length of a string is 344 cm. The string is held fixed at each end. The string vibrates in two sections; i.e., the string has two antin- odes, and the string vibrates at 130 Hz. Find the wavelength answer in m What is the fundamental …
6. ### Physics

The length of a string is 344 cm. The string is held fixed at each end. The string vibrates in two sections; i.e., the string has two antin- odes, and the string vibrates at 130 Hz. Find the wavelength. Answer in units of m. What is …
7. ### Physics

A string is fixed at both ends and vibrating at 120 Hz, which is its third harmonic frequency. The linear density of the string is 4.9x10-3 kg/m, and it is under a tension of 3.6 N. Determine the length of the string.
8. ### Physics

The fundamental frequency of the G string of a guitar is f=196Hz. The fundamental vibrational mode of the string is described by the standing wavey(t,x)=acos(2πft)sin(πxL)where L=65cm is the length of the string and a=1mm is …
9. ### Physics

A standing wave is set up in a string of variable length and tension by a vibrator of variable frequency. Both ends of the string are fixed. When the vibrator has a frequency fA, in a string of length LA and under tension TA, nA antinodes …
10. ### Physics

A string of length 2.7 m is fixed at both ends. When the string vibrates at a frequency of 90.0 Hz, a standing wave with 5 loops is formed. What is the wavelength of the waves that travel on the string?

More Similar Questions