The maximum distance that the particles of a medium move from the rest position is the

Amplitude of the wave

Explanation:

A wave consists of periodic oscillations that travel through a medium or through space, carrying energy but not matter.

A mechanical wave (such as sound) can only travel through a medium, so the oscillations of the wave are due to the displacement of the particles in the medium around their rest position.

For example, for a sound wave travelling through air, the particles of the air oscillate back and forth around their rest position, transmitting the wave through the air.

The maximum displacement of the particles from the rest position is called amplitude. Other important quantities of a wave are:

- Frequency: the number of oscillations per second

- Wavelength: the distance between two consecutive points of the wave at maximum displacement

- Period: the time between two successive oscillations

truck y has a greater velocity than truck x.