In this post, we will solve **Numerical problems based on the Sound chapter of class 8 science**. Here, first we will go through required *formulas* & other related equations, and then attempt the numerical questions. Solution & answer is given for all the numerical questions.

**Related Post**: **Light class 8 numerical solved**

**Formulas Used**

Frequency = 1 / Time Period

f = 1/TTime Period = 1/frequency

T = 1/fDistance traveled by a sound wave = speed of sound x time duration

Frequency = number of oscillations per second

Time period = time required for a single oscillation

**Sound Class 8 Numerical Questions and Answers** [solved]

Example 1.An object is vibrating at 50 hertz. What is its time period?

**Solution:**

If an object is vibrating at 50 hertz

50 = 1/T

=> T = 1/50 = 0.02 sec

Its time period will be 0.02 sec.

Example 2.1 hertz is equal to how many vibrations per minute?

**Solution:**

1 Hz= 1 vibration/second

1 minute=60 seconds,

hence 1 hertz = 60 vibrations /minute

Example 3: Lightning can be seen the moment it occurs. Paheli observes lightning in her area. She hears the sound 5 s after she observed lightning. How far is she from the place where lightning occurs? (speed of sound =330 m/s).

**Solution**

Distance=330 m/s x 5s

=1650 m

Example4: A simple pendulum makes 10 oscillations in 20 seconds. What is the time period and frequency of its oscillation?

**Solution**

Time period = time required for one oscillation =20/10 s = 2 s

frequency = 1/Time Period = 1/2 = 0.5 oscillations/sec = 0.5 Hz