A simple pendulum performs 18 oscillations per second. The mechanical wave produced by it will be

Options

A. infrasonic wave
B. ultrasonic wave
C. subsonic wave
D. electromagnetic wave

Explanation

To solve the problem, we need to determine the type of mechanical wave produced by a simple pendulum that performs 18 oscillations per second. Here’s a step-by-step solution:

### Step 1: Understand the Frequency of the Pendulum
The problem states that the simple pendulum performs 18 oscillations per second. This means that the frequency (f) of the pendulum is 18 Hz (hertz).

### Step 2: Relate Frequency to Mechanical Waves
The frequency of the mechanical wave produced by the pendulum is the same as the frequency of the pendulum itself. Therefore, the mechanical wave produced will also have a frequency of 18 Hz.

### Step 3: Identify the Type of Wave Based on Frequency
Next, we need to classify the frequency of 18 Hz:
- The audible range for humans is from 20 Hz to 20,000 Hz (20 kHz).
- Frequencies below 20 Hz are classified as infrasonic waves.
- Frequencies above 20 kHz are classified as ultrasonic waves.

Since 18 Hz is below 20 Hz, it falls into the infrasonic category.

### Step 4: Choose the Correct Option
Based on our analysis, the mechanical wave produced by the pendulum is an infrasonic wave. Therefore, the correct answer is option 1: infrasonic wave.

### Final Answer
The mechanical wave produced by the pendulum will be an **infrasonic wave**.

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