Question

A sound wave has a frequency of 500 Hz and wavelength 80 cm. How long will it take to travel 1 km?

• A. 2.5 seconds
• B. 25 seconds
• C. 25 minutes
• D. 2.5 minutes

Hint:

The speed of sound can be found by multiplying the frequency and wavelength. Use this to find the time for the sound to travel a specific distance.

Answer 1

The Correct Option is A

The speed of sound \( v \) is given by the formula: \[ v = f \times \lambda \] Where: - \( f = 500 \, \text{Hz} \) (frequency) - \( \lambda = 80 \, \text{cm} = 0.8 \, \text{m} \) (wavelength) Substitute the values: \[ v = 500 \times 0.8 = 400 \, \text{m/s} \] Now, time \( t \) to travel 1 km: \[ t = \frac{\text{distance}}{\text{speed}} = \frac{1000}{400} = 2.5 \, \text{seconds} \] Thus, the correct answer is 2.5 seconds.