The natural frequency of a system is determined by its physical properties, such as mass, stiffness, and damping. In general, a decrease in mass will lead to an increase in the natural frequency of the system.

To understand why, consider a simple mass-spring system. The natural frequency of this system is given by the formula:

```

f = 1 / (2π) * √(k/m)

```

where:

* f is the natural frequency in Hertz (Hz)

* k is the spring stiffness in Newtons per meter (N/m)

* m is the mass of the system in kilograms (kg)

As you can see from the formula, the natural frequency is inversely proportional to the square root of the mass. This means that if the mass decreases, the natural frequency will increase.

The same principle applies to other types of systems, such as pendulums and vibrating strings. In general, a decrease in mass will lead to an increase in the natural frequency of the system.