Final answer:
Capacity is directly related to volume, as volume is the measure of the physical space an object occupies. However, it is not directly related to length or mass.
Step-by-step explanation:
The capacity of an object is directly related to its volume, which is the measure of physical space it occupies. The volume of an object is measured in cubic units, such as cubic centimeters or liters. For example, a larger container has a greater volume and can hold more. Therefore, volume is directly related to capacity.
On the other hand, mass is a measure of the amount of material within an object, and it is not directly related to capacity. The density of an object is another factor impacting its capacity, as density is the mass divided by the volume. However, density is not a direct factor influencing capacity.
In summary, capacity is directly related to volume, but not to length or mass.