The source of every sound is something that is

Question

A) undergoing simple harmonic motion.

B) accelerating.

C) a net emitter of energy.

D) moving.

E) vibrating.

Answer 1

E is probably what they want.

But A or D are also valid

.

Answer 2

e)vibrating

Answer 3

E

Answer 4

Vibrating

Answer 5

I think the answer they want is E, but its wrong.

You can produce sound by heating and cooling an object. This in turn heats the air, and causes sound, but the source of the sound is NOT vibrating.

They may also claim A, which is also false. Almost no natural sources of sound are SHM.

Answer 6

The only correct answer is C, because we are asked for a feature of EVERY sound source.

C is correct because every sound possesses energy.  So, whatever created that sound must have released some energy.

On the other hand, all the other answers are wrong because they describe what the sources of SOME sounds can be. Here are specific examples of sounds which can be used to invalidate each wrong answer (some counterexamples invalidate several):

A) A violin string does not undergo simple harmonic motion (it has very substantial high-order hamonics).  A tuning fork is much closer to simple harmonic motion but no real object moves in perfect harmonic motion.

B) Uniform (nonaccelerating) motion can cause turbulences in the surrounding air which produce sound.  Think of a siren (essentially a rotating wheel with paddles) at constant speed.

D) Thunder is NOT produced by motion.

E) The wave front of an explosion is not vibrating (think of an A-bomb).

This is a very good multiple-choice question because it makes you THINK.about the physics and requires flawless logic too. Sound is a form of motion and vibration but its source need not be.

Answer 7

E, you don't get sound without vibration