Masses MA and MB hanging from the ends of strings of lengths LA and LB...
To understand why the correct answer is option 'C', let's break down the given information and analyze the relationship between the frequencies and lengths of the strings.
Given:
- Masses MA and MB are hanging from strings of lengths LA and LB, respectively.
- The masses are executing simple harmonic motions.
- The frequency of MA, fA, is twice the frequency of MB, fB.
Frequency of Simple Harmonic Motion:
The frequency of an object executing simple harmonic motion is given by the formula:
f = 1/2π * √(k/m)
where f is the frequency, k is the spring constant, and m is the mass of the object.
Analyzing the Given Information:
1. Frequency Relationship:
Since fA = 2fB, we can write the equation as:
1/2π * √(kA/MA) = 2 * (1/2π * √(kB/MB))
Simplifying this equation, we get:
√(kA/MA) = 2 * √(kB/MB)
Squaring both sides of the equation, we have:
kA/MA = 4 * (kB/MB)
2. Length Relationship:
The length of a simple pendulum affects its frequency. The formula for the frequency of a simple pendulum is:
f = 1/2π * √(g/L)
where g is the acceleration due to gravity and L is the length of the pendulum.
Since the lengths of the strings are LA and LB, we can write the equation as:
1/2π * √(g/LA) = 2 * (1/2π * √(g/LB))
Simplifying this equation, we get:
√(g/LA) = 2 * √(g/LB)
Squaring both sides of the equation, we have:
g/LA = 4 * (g/LB)
Simplifying further, we can cancel out g from both sides:
1/LA = 4 * (1/LB)
LA = LB/4
Conclusion:
From the analysis above, we can conclude that the correct answer is option 'C':
LA = LB/4, regardless of the masses.
This means that the length of the string for mass A is four times smaller than the length of the string for mass B, irrespective of the masses of the objects.