To measure the density of an irregularly shaped object using an Eureka can (also known as a displacement can), you need to determine both its mass and its volume. The Eureka can is specifically used to accurately measure the volume of an object by water displacement, a principle based on Archimedes' Principle.
Understanding Density
Density is a fundamental physical property of matter that describes how much mass is contained in a given volume. It is calculated using the formula:
$$\text{Density (ρ)} = \frac{\text{Mass (m)}}{\text{Volume (V)}}$$
Where:
- Mass (m) is typically measured in grams (g) or kilograms (kg).
- Volume (V) is typically measured in cubic centimeters (cm³) or milliliters (mL) for liquids and solids, or cubic meters (m³).
- Density (ρ) is expressed in units like g/cm³ or kg/m³.
Measuring Density Using an Eureka Can: A Step-by-Step Guide
The process involves two main stages: measuring the object's mass and then measuring its volume using the Eureka can.
1. Measuring the Mass of the Object
Before using the Eureka can, you must find the mass of the object whose density you wish to determine.
- Step 1: Use a Balance: Place the object (e.g., a stone, a metal lump) on a digital or triple beam balance.
- Step 2: Record Mass: Accurately measure and record the mass of the object. For example, if the stone weighs 150 grams.
2. Measuring the Volume of the Object Using an Eureka Can
This is where the Eureka can comes into play, utilizing the principle that the volume of water displaced by a submerged object is equal to the volume of the object itself.
- Step 1: Set up the Eureka Can:
- Place the Eureka can on a flat, stable surface.
- Fill the displacement can until the water is level with the bottom of the pipe (spout). Ensure no water is dripping from the spout at this point.
- Step 2: Prepare for Collection:
- Place a measuring cylinder (graduated cylinder) under the pipe (spout) ready to collect the displaced water. Make sure the cylinder is clean and dry to ensure accurate volume measurement.
- Step 3: Submerge the Object:
- Carefully drop the stone (or object) into the can. Lower it gently to avoid splashing and losing any water. Splashing can lead to inaccurate volume measurements.
- Wait until no more water runs into the cylinder. Allow all the displaced water to flow out of the spout and collect in the measuring cylinder.
- Step 4: Measure Displaced Water Volume:
- Once the water has stopped dripping, carefully remove the measuring cylinder.
- Measure the volume of the displaced water collected in the measuring cylinder. Read the volume at eye level from the bottom of the meniscus (the curved surface of the water). This volume is equal to the volume of your object.
3. Calculating the Density
Once you have both the mass and the volume, you can calculate the density.
- Step 1: Apply the Formula: Use the density formula:
$$\text{Density} = \frac{\text{Mass}}{\text{Volume}}$$ - Step 2: Substitute Values: Plug in the measured mass and volume.
Example Calculation:
Let's say you measured:
- Mass of the stone (m) = 150 g
- Volume of displaced water (V) = 50 cm³ (which is the volume of the stone)
Then, the density of the stone would be:
$$\text{Density} = \frac{150 \text{ g}}{50 \text{ cm}^3} = 3 \text{ g/cm}^3$$
Summary of Steps
| Step | Action | Tool | Output |
|---|---|---|---|
| 1 | Measure mass of the object | Balance (digital/beam) | Mass (g) |
| 2 | Fill Eureka can to spout level | Eureka Can, Water | Ready setup |
| 3 | Place measuring cylinder under spout | Measuring Cylinder | Collection ready |
| 4 | Gently drop object into can | Object, Eureka Can | Water displacement |
| 5 | Wait for all water to collect | Eureka Can, Cylinder | Full collection |
| 6 | Read volume of displaced water | Measuring Cylinder | Volume (cm³) |
| 7 | Calculate density (Mass ÷ Volume) | Calculator | Density (g/cm³) |
Tips for Accuracy
- Handle with Care: Always handle the object gently when placing it in the can to prevent splashing.
- No Air Bubbles: Ensure no air bubbles are trapped on the object when submerged, as this would lead to an inaccurate volume reading.
- Read Meniscus Correctly: For water, always read the volume from the bottom of the meniscus at eye level.
- Repeat Measurements: For better accuracy, perform multiple trials and calculate the average mass and volume.
- Dry Object: If the object is porous, it might absorb water, leading to an inaccurate volume. The Eureka can is best for non-porous, irregularly shaped solids.
By following these steps, you can accurately measure the density of an irregularly shaped object using an Eureka can.
