Fluids Demonstration: Measure Volume of Irregularly Shaped Object
by Ron Kurtus (revised 3 May 2007)
Suppose you want to show or demonstrate how to measure the volume of an irregularly shaped object. While you can easily measure the volume of a rectangular object by measuring the lengths of the sides, that technique does not work for an irregularly shaped object.
The solution to this problem is based on the fact that volume is the space an object takes up. If the object is immersed in water, it will displace water equal to the volume of the object. The problem then is to measure the water displaced by the object. A clever way of doing that is to place the object in a bucket that is filled to the top. Then you collect the displaced water that overflows from the bucket.
You can easily measure the volume of the displaced water to find the volume of the object. You can verify the method works by trying it with an object of known volume. A drawback of this method is when the object is bigger than any available container. A problem with this method is if the object is bigger than any available container.
You can easily measure the volume of a rectangular object by measuring the lengths of the sides. The volume (V) of a box is its length (L) times width (W) times height (H) or V = L*W* H.
But suppose you had an object that had an irregular shape. How would you measure its volume? One way would be to immerse the object in a full container of water and measuring the volume of the replaced water.
Measuring the volume of irregularly shaped objects by immersion can be an idea for a science project in the area of physical science or physics. The biggest problem is in verifying that your results are correct. You could establish an empirical rule using known volumes before using the method on unknown volumes.
Questions you may have include:
- What is the purpose of the experiment?
- What research must be done?
- What is the experiment?
This lesson will answer those questions.
Purpose of experiment
The purpose of the experiment is to first verify the method of determining the volume of small objects by measuring the volume of spill-off water after immersion of the object.
Then this method can be used to measure the volume of irregularly shaped objects.
Do some research the basic principles of fluids, as well as other experiments using this method to measure the volume of objects.
Use the law that an object displaces its volume in water to determine the volume of the object.
You know that water takes the shape of its container. You also know that if you put an object in a full bucket of water, the excess water will spill out the bucket.
Now, if you put a can or bottle full of water into the bucket, the amount that spills out will be almost the same as the amount of liquid in the bottle (less the thickness of the bottle).
You can try putting a sealed soft drink bottle full of water into a bucket full of water. Collect the water that flows over the top of the bucket. Pour that water into a second soft drink bottle of the same size. The amount of water should be just about the same.
Therefore, if you put any object in a full container of water, the amount that spills out will be the same as the volume of the object.
- Irregularly shaped object
- Container or bucket that is large enough to put the object in
- Pan to place under the bucket
- Gradated flask to measure volume of liquid
- Full the bucket with water up to its brim.
- Place the bucket in the pan.
- Carefully place object in water.
- Collect water that overflows into the pan.
- Measure the volume of overflow water.
This experiment shows an application of the principle that objects displace their volume in a liquid.
You can demonstrate how to measure the volume of an irregularly shaped obejct by measuring overflow runoff.
Try something clever
Resources and references
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Fluids Experiment: Measure Volume of Irregularly Shaped Object