Depending on the size of the rock - if it is small enough it can be measured in a container with water the size can be judged by seeing how much water it displaces
the water displacement method
When you are trying to find the volume of an irregularly shaped object.
break it up into pieces you know how to find the volume of
Use a measuring cylinder with water in it. Note down the volume of water in the cylinder, then add the solid. Note down the new volume and subtract the first value from the second to get the volume of the solid.
It depends on what the second method is!
You can find the volume of an irregularly shaped object, like a rock, by using the water displacement method. Submerge the object in a known volume of water in a container. Measure the increase in water level, which equals the volume of the rock.
The volume of an irregularly shaped solid can be measured by placing the solid in a known quantity of water in a container with measurement markings. Take the new volume and find the difference between this and the old volume. This is the volume of your irregularly shaped solid.
It is the displacement method.
Mass divided by Volume = Density. Or use the displacement method for an irregularly shaped object.
Google "Archimedes' Principle" and see if that gives you a clue...
The volume of an irregularly shaped geometric object is typically determined by the amount of water it displaces when submerged. This method utilizes the principle of fluid displacement to calculate the volume of the object. By measuring the amount of water the object displaces, one can determine its volume.
The volume of the object is 7ml.