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A wave moving with constant speed on a u...

A wave moving with constant speed on a uniform string passes the point `x=0` with amplitude `A_0`, angular frequency `omega_0` and average rate of energy transfer `P_0`. As the wave travels down the string it gradually loses energy and at the point `x=l`, the average rate of energy transfer becomes`P_0`/2. At the point `x=l`. Angular frequency and amplitude are respectively:

A

`omega_(0)"and "(A_(0))/(sqrt(2))`

B

`omega_(0)/(sqrt(2))"and"A_(0)`

C

less then `omega_(0)` and `A_(0)`

D

`(omega_(0))/(sqrt(2))` and `(A_(0)0/(sqrt(2))`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze how the amplitude and angular frequency of a wave change as it travels down a string while losing energy. ### Step-by-Step Solution: 1. **Understanding the Energy Transfer Relation**: The average rate of energy transfer \( P \) for a wave on a string is given by the formula: \[ P = \frac{1}{2} \mu A^2 \omega^2 V \] where: - \( \mu \) is the linear mass density of the string, - \( A \) is the amplitude of the wave, - \( \omega \) is the angular frequency, - \( V \) is the speed of the wave. 2. **Initial Conditions**: At the point \( x = 0 \): - Amplitude = \( A_0 \) - Angular frequency = \( \omega_0 \) - Average rate of energy transfer = \( P_0 \) Thus, we can write: \[ P_0 = \frac{1}{2} \mu A_0^2 \omega_0^2 V \] 3. **Energy Transfer at Point \( x = l \)**: At the point \( x = l \), the average rate of energy transfer becomes: \[ P = \frac{P_0}{2} \] Let the new amplitude at this point be \( A' \) (which we need to find), while \( \omega \) remains constant at \( \omega_0 \). Therefore, we can write: \[ \frac{P_0}{2} = \frac{1}{2} \mu (A')^2 \omega_0^2 V \] 4. **Setting Up the Equations**: From the first equation: \[ P_0 = \frac{1}{2} \mu A_0^2 \omega_0^2 V \] From the second equation: \[ \frac{P_0}{2} = \frac{1}{2} \mu (A')^2 \omega_0^2 V \] 5. **Dividing the Equations**: Dividing the second equation by the first gives: \[ \frac{\frac{P_0}{2}}{P_0} = \frac{\frac{1}{2} \mu (A')^2 \omega_0^2 V}{\frac{1}{2} \mu A_0^2 \omega_0^2 V} \] Simplifying this, we get: \[ \frac{1}{2} = \frac{(A')^2}{A_0^2} \] 6. **Solving for \( A' \)**: Rearranging gives: \[ (A')^2 = \frac{A_0^2}{2} \] Taking the square root: \[ A' = \frac{A_0}{\sqrt{2}} \] 7. **Angular Frequency**: Since the angular frequency \( \omega \) remains constant, we have: \[ \omega' = \omega_0 \] ### Final Result: At the point \( x = l \): - Amplitude \( A' = \frac{A_0}{\sqrt{2}} \) - Angular frequency \( \omega' = \omega_0 \)
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