The maximum speed an object will reach when falling through a substance, such as air, is called .

The maximum speed an object reaches when falling through a substance like air is called terminal velocity. Terminal velocity occurs when the force of gravitational pull downward is balanced by the drag force acting upward against the motion of the object. At this point, the object falls at a constant speed and will not accelerate further.

The value of terminal velocity depends on several factors including the mass and shape of the object, as well as the density of the fluid (in this case, air) through which it is falling. Terminal velocity is a crucial concept in physics, particularly in understanding the dynamics of falling objects in fluid environments.