Explanation:

**Introduction:**
Knocking is a phenomenon that occurs in spark-ignition (SI) engines when the air-fuel mixture in the combustion chamber detonates instead of burning smoothly. This can cause damage to the engine and reduce its performance. The knocking tendency is influenced by various factors, and in this case, we need to determine how it is affected by increasing engine speed.

**Effect of Engine Speed on Knocking Tendency:**
The knocking tendency in a SI engine reduces with increasing engine speed. This is due to the following reasons:

1. **Increased Turbulence:** At higher engine speeds, there is increased turbulence in the combustion chamber. This leads to better mixing of the air-fuel mixture, resulting in a more uniform and controlled combustion process. As a result, the chances of knocking are reduced.

2. **Reduced Residence Time:** At higher engine speeds, the time available for the air-fuel mixture to burn is reduced. This means that the combustion process is completed more quickly, leaving less time for abnormal combustion to occur. This reduces the likelihood of knocking.

3. **Reduced Heat Transfer:** At higher engine speeds, the rate of heat transfer from the combustion chamber walls to the incoming air-fuel mixture is reduced. This is because the increased turbulence promotes better mixing, which helps to distribute the heat more evenly throughout the combustion chamber. As a result, the temperature of the air-fuel mixture is kept lower, reducing the chances of knocking.

4. **Improved Cooling:** Higher engine speeds often require better cooling systems to dissipate the increased heat generated. This improved cooling helps to maintain lower combustion chamber temperatures, which in turn reduces the knocking tendency.

**Conclusion:**
In conclusion, the knocking tendency in a SI engine reduces with increasing engine speed due to factors such as increased turbulence, reduced residence time, reduced heat transfer, and improved cooling. These factors collectively contribute to a more controlled and uniform combustion process, minimizing the chances of knocking.

As you increase the engine speed there is less time to ignite  mass fuel and web front travel easily and knocking tendency decress.