Part A: A lightening strike 2 km away creates a sound of thunder by making a sho

Question

Part A:

A lightening strike 2 km away creates a sound of thunder by making a shock wave in air from the large energy it deposits so quickly that the air cannot move out of the way. Pick those that are correct if f the speed of sound is about 340 meters/second in the night air. at 20 degrees Celsius.

a. The bang occurs before the flash

b. The booms are so loud that the shock wave goes nearly at the speed of light and they occur at the same time as the flash

c. The lightning flash comes before the bang by 6 seconds

d. You can find the distance to the strike from the delay: each mile is about 5 seconds

Part B:

A cello is similar to a violin, with 4 longer strings and a larger body. The highest frequency string is A3 at 220 Hz (one octaves below A440 on an equally tempered scale).   The string is often made of tungsten to give a tough dense material with a mass of about 1.5 grams per meter. What tension would you apply to tune this string to a fundamental at  220 Hz if it is 0.695 meters long? Remember that the string is fixed at both ends.

a. about 140 N

b. about 35 N

c. about 1.4 N

d. about 140,000 N

Part C:

A sound wave in air is (pick those answers that are appropriate)

a. A propagating compression of the air followed by a "rarefaction" when the density drops, with the denser regions separated by a wavelength moving through the gas

b. A movement of molecules locally to reduce or increase the pressure, but no bulk motions of air.

Bulk motion of the air at the speed of sound from its source to the detector or your ear.

d. A disturbance that locally produces a change in pressure at the frequency of sound, but if you took a snapshot picture would show dense regions separated by a wavelength.

a. A propagating compression of the air followed by a "rarefaction" when the density drops, with the denser regions separated by a wavelength moving through the gas

b. A movement of molecules locally to reduce or increase the pressure, but no bulk motions of air.

Bulk motion of the air at the speed of sound from its source to the detector or your ear.

d. A disturbance that locally produces a change in pressure at the frequency of sound, but if you took a snapshot picture would show dense regions separated by a wavelength.

Explanation / Answer

Since all parts are separate questions so answering first part

Part A

time by sound=2000/340=5.88 sec

time by light=2000/300000000=6.6*10^(-6) sec

so light occur first

The lightning flash comes before the bang by 6 seconds

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