A measuring cylinder is used to find the volume of irregular objects through a simple method based on water displacement.
The volume of an irregular object cannot be easily calculated using standard geometric formulas because it doesn't have straight edges or a uniform shape. However, we can determine its volume by measuring how much liquid it displaces when fully submerged. This technique is called the water displacement method, often attributed to the ancient Greek scientist Archimedes.
As stated in the reference, "the volume of an irregular solid is equal to the volume of water displaced by it when it is immersed in water. When we immerse an irregular body in water, it displaces some amount of water." A measuring cylinder is the ideal tool for this because it allows for precise measurement of liquid volumes.
Here's how you typically use a measuring cylinder for this purpose:
Steps for Measuring the Volume of an Irregular Object
This method relies on the principle that the submerged object pushes aside (displaces) a volume of liquid exactly equal to its own volume.
- Add a known volume of liquid: Pour a suitable amount of liquid (usually water) into the measuring cylinder. The amount should be enough to completely cover the object without overflowing when the object is added. Note this initial volume carefully.
- Submerge the irregular object: Gently place the irregular object into the measuring cylinder. Ensure it is fully submerged and no air bubbles are clinging to it. If the object floats, this method needs modification (e.g., using a sinker of known volume).
- Read the new liquid volume: Observe and record the new volume of the liquid in the measuring cylinder with the object submerged. The liquid level will have risen due to the displaced liquid.
- Calculate the volume of the object: Subtract the initial volume of liquid from the final volume. The difference is the volume of the irregular object.
Example Calculation
Let's say you follow these steps:
- Initial volume of water (V₁): 50 mL
- Final volume of water with object submerged (V₂): 75 mL
The volume of the irregular object is calculated as:
Volume of Object = V₂ - V₁
Volume of Object = 75 mL - 50 mL
Volume of Object = 25 mL
Since 1 mL is equal to 1 cubic centimeter (cm³), the volume of the object is 25 cm³.
Key Points to Remember
- Use a measuring cylinder with appropriate capacity and precision for the object being measured.
- Read the liquid level at the bottom of the meniscus (the curve of the liquid surface).
- Ensure the object is fully submerged.
- This method works best for objects that do not dissolve in or react with the liquid and are dense enough to sink.
By accurately measuring the displacement of liquid, a measuring cylinder provides a reliable way to determine the volume of irregularly shaped objects.
