Question:medium

A source of sound of frequency 500Hz is moving towards an observer with velocity $30m/s$. The speed of sound is $330m/s$. The frequency heard by the observer will be:

Show Hint

Source moves towards = Frequency increases. If the source velocity is 10% of sound speed, the frequency increases by roughly 10%.
  • 450 Hz
  • 550 Hz
  • 600 Hz
  • 500 Hz
Show Solution

The Correct Option is B

Solution and Explanation

Step 1: Understanding the Concept:
This problem involves the Doppler Effect. When a source of sound moves toward a stationary observer, the wave fronts are "bunched up," causing the observer to perceive a higher frequency than the one actually emitted.
Step 2: Key Formula or Approach:
The apparent frequency \(f'\) is given by: \[ f' = f \left( \frac{v}{v - v_s} \right) \] Where \(v\) is the speed of sound and \(v_s\) is the velocity of the source.
Step 3: Detailed Explanation:
Given: \(f = 500\) Hz, \(v = 330\) m/s, and \(v_s = 30\) m/s. Substituting the values into the formula: \[ f' = 500 \left( \frac{330}{330 - 30} \right) \] \[ f' = 500 \left( \frac{330}{300} \right) \] \[ f' = 500 \times 1.1 = 550 \text{ Hz} \]
Step 4: Final Answer:
The frequency heard by the observer is 550 Hz.
Was this answer helpful?
0