Q:

Which instrument or method can be used to find the volume of a marble?

A:

Perhaps the easiest way to find the volume of a marble is through **Archimedes's ****principle**. This is a principle of the **displacement of water **that is named after the Greek mathematician Archimedes. This principle states that when an object is fully submerged in water, the volume of water displaced (moved) by the object will be equal to the volume of the object.

The instrument needed is a **graduated cylinder**. This is a (usually glass) container that indicates volumes, usually in milliliters (mL).

In real terms, this means that when an object is placed into water and fully submerged (covered), the water level will rise by an amount that is equivalent to the volume (size) of the object. The method goes as follows:

Measure out an amount of water into a graduated cylinder large enough to fit the marble. Note the volume of water indicated on the graduated cylinder and write it down. Next, place the marble gently into the water. The water level will rise due to displacement. Note the new level of the water. Subtract the two water levels (the new, higher level minus the previous one). This is equal to the volume of the marble in milliliters. 1 milliliter is equivalent to 1 cubic centimeter. Suppose we started with 2 milliliters of water and the water rose to 2.5 milliliters after dropping the marble into the water. The marble's volume would be equal to .5 mL or `.5 cm ^3` .``