Question

You are making a telephone out of two aluminum cans and some string. You can choose between two types of string: a 2-m length of thin cooking twine or a 2-m length of heavy rope, both used at the same tension. Which type of string should you use so that you have the fastest wave speed in your telephone?

Answer 1

Answer:

C)You should use the thin cooking twine.

Explanation:

A)You can choose either because they are the same length and will produce the same wave speed.

B)You should use the heavy rope.

C)You should use the thin cooking twine.

The speed of wave in a string is given by the following formula:

|$v$| = $\sqrt{\frac{F_T}{u} }$

Where |$v$| = speed of wave, $F_T$ = tension in the string, and μ = mass per length of the string.

Even though the two strings have the same length, the μ (mass/length) for the heavy rope will be more than the that of a thin rope. Consequently, the $F_T$:μ for the thin rope will be higher than that of the heavy rope and as such, gives a bigger |$v$|.

Therefore, the thin rope should be used in order to get a faster wave speed in the telephone.

The correct option is C.