In a vibrating-string experiment,three loops are observed between points A and B when the mass on one end of the string is 100 g.The number of loops between A and B can be changed to two by replacing the 100-g mass with a mass of
A)150 g
B)225 g
C)44.4 g
D)66.7 g
E)300 g

Question

In a vibrating-string experiment,three loops are observed between points A and B when the mass on one end of the string is 100 g.The number of loops between A and B can be changed to two by replacing the 100-g mass with a mass of 
A)150 g 
B)225 g 
C)44.4 g 
D)66.7 g 
E)300 g

Quizplus · Accepted Answer

From the problem, we can deduce that increasing the mass will decrease the number of loops observed between A and B. This is because a higher mass will result in a lower frequency and thus a longer wavelength.

To decrease the number of loops from 3 to 2, we need to decrease the wavelength by a factor of 3/2. This means increasing the mass by a factor of (3/2)^2 = 2.25.

So, the mass needed to create 2 loops is 100 g x 2.25 = 225 g, which is choice (B).

In a Vibrating-String Experiment,three Loops Are Observed Between Points a and B