**Category:** Wave Mechanics  
**Subtype:** Wave Propagation  

**Problem Description:** This problem involves a mechanical wave traveling along a long elastic string. It provides information about the amplitude of the wave, the displacement of two points on the string, their velocities, and the distance between them. The goal is to find the speed of the wave traveling along the string.  

**Key Elements:**  
- Amplitude of the wave: 6 mm  
- Displacement of two points: 3 mm (moving in opposite directions)  
- Velocity of the points: \(0.3 \pi \sqrt{3} \, \text{cm/s}\)  
- Minimum distance between the points: 8 cm  

**Objective:** Calculate the wave speed on the string.