It is a graduated cylinder.
Volume displacement.
in 15
V = radius2 x Pi x length
The volume of the metal cylinder is 21.4mL - 15mL = 6.4mL. This is the water displacement method for determining the volume of an irregular solid.
A label on a bottle bought in a shop would show the volume. If there is no label, fill the bottle with water to the top, then empty the water into a measuring jar or cylinder. The volume is then read off the scale marked on the measuring jar or cylinder.
This is a poor question. There is no way such a method can measure the volume of a sugar cube, for example, because it will dissolve in the water.
It should say on the cylinder. Most of the ones I've seen are marked every 1 or 2 ml and labelled every 10 ml, or marked every 0.1 ml and labelled every ml.
Fill the cylinder with water to a marked point. Then place the rock in the water and measure how much the water level rises. That will give you the amount of volume displaced by the rock and so the volume of the rock.
The method for determining the volume of a solid depends on its shape. The volume of a solid object with a regular geometric shape (rectangular box, cube, cylinder, sphere) can be determined using the volume formula for the shape. Because many objects are not regularly shaped their volume cannot be determined using a volume formula. The volume of these objects can be found by water displacement. A volume of water sufficient to cover the object is placed in a graduated cylinder and the volume read. The object is added to the cylinder and the volume read again. The difference between the two volumes is the volume of the object.
I've used a lot of beakers, and they're marked on the side. You just fill it to the line you want to use.
A graduated cylinder may be used for small objects that are insoluble in a selected liquid. But that method would not work for determining the volume of a sugar cube (soluble in water) or a motor car (won't fit in a graduated cylinder!).
volume of cylinder pir2h