Measuring the volume of an irregular solid

 Measuring the volume of an irregular solid :

Aim: To measure the volume of an irregularly shaped object, such as a rock or key, using a Eureka can. 

Materials: 

• Eureka can (displacement can)

• Measuring cylinder

• Beaker or small tray

• An irregular solid (e.g., a small rock, key, or block of plasticine)

• String or thread

• Water 

• Balances

Instructions: 

1. Prepare the Eureka can. Place the Eureka can on a flat surface, such as a lab bench, and fill it with water until the water begins to dribble out of the spout.

2. Wait and prepare. Allow all the excess water to drip out until the spout stops dripping. Place an empty measuring cylinder directly under the spout to collect the displaced water.

3. Submerge the object. Tie a piece of string around your irregular object. Carefully and slowly lower the object into the can until it is completely submerged. Avoid splashing, as this would cause a measurement error.

4. Collect the displaced water. Wait for the water to stop dripping from the spout into the measuring cylinder.

5. Measure the volume. Read the volume of the collected water from the measuring cylinder. Look at the water level at eye level and read from the bottom of the meniscus (the curved surface of the water) for the most accurate measurement.

6. Record your result. The volume of the water collected in the measuring cylinder is equal to the volume of your irregular solid. 

Extensions for Year 7: 

• Compare with a regular object: Use the same method with a regularly shaped object, such as a cube, whose volume can be calculated using a formula (

• volume=length×width×height o l u m e equals l e n g t h cross w i d t h cross h e i g h t

• 𝑣𝑜𝑙𝑢𝑚𝑒=𝑙𝑒𝑛𝑔𝑡ℎ×𝑤𝑖𝑑𝑡ℎ×ℎ𝑒𝑖𝑔ℎ𝑡). Compare the two results to demonstrate the accuracy of the displacement method.

• Calculate density: Introduce the concept of density (

• density=mass/volumed e n s i t y equals m a s s / v o l u m e

• 𝑑𝑒𝑛𝑠𝑖𝑡𝑦=𝑚𝑎𝑠𝑠/𝑣𝑜𝑙𝑢𝑚𝑒). Use a digital balance to find the mass of the irregular object and then use the volume measured by the Eureka can to calculate its density.

• Explore buoyancy: Challenge students to use the can to investigate if different materials, like wood or a plastic toy, float or sink. They can observe how floating objects displace a volume of water equal to their own weight, not their full volume.