Explanation:

A spring-controlled governor is used to regulate the speed of machines such as steam engines, turbines, etc. The governor consists of two main parts: a rotating ball or weight and a spring. The ball or weight moves up and down with the shaft and controls the speed of the machine. The spring works to maintain the equilibrium of the governor.

If the spring stiffness of the governor is too low or the ball weight is too high, the governor can become unstable. This means that the ball or weight oscillates wildly and cannot control the speed of the machine properly. To make the governor stable, the spring stiffness needs to be increased or the ball weight needs to be decreased.

Reasons:

There are a few reasons why decreasing the spring stiffness can make the governor stable:

1. It reduces the natural frequency of the governor: The natural frequency is the frequency at which the governor oscillates without any external force. If the natural frequency of the governor is too high, it can become unstable. Decreasing the spring stiffness reduces the natural frequency of the governor, making it more stable.

2. It reduces the sensitivity of the governor: Sensitivity is the amount of change in speed that the governor produces for a given change in the position of the ball or weight. If the governor is too sensitive, it can become unstable. Decreasing the spring stiffness reduces the sensitivity of the governor, making it more stable.

3. It increases the damping of the governor: Damping is the ability of the governor to resist oscillations. If the damping of the governor is too low, it can become unstable. Decreasing the spring stiffness increases the damping of the governor, making it more stable.

Conclusion:

In conclusion, decreasing the spring stiffness of a spring-controlled governor can make it stable. This is because it reduces the natural frequency, reduces the sensitivity, and increases the damping of the governor.