Volume of odd-shaped objects by displacement
Lower a stone, a key, a marble and a toy into water and measure how much the water rises. Use an overflow can for a stone too big for the cylinder.
Core concept
In short: Drop a stone in water and see the water rise by the stone's own volume.
An object sunk in water pushes aside (displaces) its own volume of water
Topic: Measurement
You cannot measure the volume: How much space something takes up, measured in millilitres or cubic centimetres. All key words of a stone with a ruler because it has no straight sides. Instead, lower it into water. The stone pushes aside, or displaces, exactly its own volume of water, so the water level rises by that amount. Volume of the object = reading after − reading before. 1 mL of water takes up 1 cm³ of space. If the object is too big for a measuring cylinder, fill an overflow can to its spout, lower the object in, and measure the water that overflows.
What you will learn
- Measure the volume of an irregular solid by displacement.
- Calculate volume as reading after minus reading before.
- Use an overflow can for large objects.
Before you start
- Read a measuring cylinder at the bottom of the meniscus.
Materials
- A stone, a key, a marble, a small plastic toy and a big stone
- Thread
Equipment
- 100 mL measuring cylinder
- Overflow (Eureka) can and a 250 mL measuring cylinder
Procedure
- Note the reading of the water in the cylinder (50 mL).
- Lower the stone in on a thread, read the new level and record it.
- Repeat with at least two other objects.
- Try the big stone, then measure it with the overflow can.
How this simulation is simplified
- Every object sinks and soaks up no water.
- The cylinder starts with 50 mL of water and the overflow can is filled to its spout.