**Category:** Wave Physics  
**Subtype:** Standing Waves  
**Problem Description:** This problem involves a vibrating string (or elastic cord) that is fixed at one end and attached to a tuning fork at the other end. It describes the formation of standing waves on the string when the tuning fork vibrates at a frequency of 40 Hz, resulting in 4 antinodes (or wave crests). The task is to find the speed of the wave traveling along the string.

**Key Information:**
- Length of the string (L) = 100 cm = 1 m
- Frequency (f) = 40 Hz
- Number of antinodes = 4
- The fixed end (B) is a node, and the end attached to the tuning fork (A) is also a node.

**Objective:** Calculate the wave speed (v) on the string.