Calculating density activity - Free Printable

Let's solve each part of this "Calculating Density" worksheet step by step. The formula for density is:

$$
\text{Density} = \frac{\text{Mass}}{\text{Volume}} \quad \text{(D = m/v)}
$$

We'll use the water displacement method to find volume, which means:
- Volume of object = Final water level – Initial water level (in mL)

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🔹 1. Rock

- Mass of rock: 20 grams
- Initial water level: 50 mL
- Final water level (with rock): 70 mL

Volume of rock:
$$
70\,\text{mL} - 50\,\text{mL} = 20\,\text{mL}
$$

Density:
$$
\frac{20\,\text{g}}{20\,\text{mL}} = 1.0\,\text{g/mL}
$$

✔ Answer:
- Volume = 20 mL
- Density = 1.0 g/mL

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🔹 2. Key

- Mass of key: 35 grams
- Initial water level: 40 mL
- Final water level (with key): 80 mL

Volume of key:
$$
80\,\text{mL} - 40\,\text{mL} = 40\,\text{mL}
$$

Density:
$$
\frac{35\,\text{g}}{40\,\text{mL}} = 0.875\,\text{g/mL}
$$

✔ Answer:
- Volume = 40 mL
- Density = 0.875 g/mL

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🔹 3. Sharpener

- Mass of sharpener: 15 grams
- Initial water level: 50 mL
- Final water level (with sharpener): 60 mL

Volume of sharpener:
$$
60\,\text{mL} - 50\,\text{mL} = 10\,\text{mL}
$$

Density:
$$
\frac{15\,\text{g}}{10\,\text{mL}} = 1.5\,\text{g/mL}
$$

✔ Answer:
- Volume = 10 mL
- Density = 1.5 g/mL

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✔ Final Answers Summary:

#### Rock
- Mass: 20 g
- Volume: 70 mL – 50 mL = 20 mL
- Density: $ \frac{20}{20} = \boxed{1.0} $ g/mL

#### Key
- Mass: 35 g
- Volume: 80 mL – 40 mL = 40 mL
- Density: $ \frac{35}{40} = \boxed{0.875} $ g/mL

#### Sharpener
- Mass: 15 g
- Volume: 60 mL – 50 mL = 10 mL
- Density: $ \frac{15}{10} = \boxed{1.5} $ g/mL

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📝 Explanation:

- Density tells us how tightly packed matter is in an object.
- Objects with higher density sink in liquids with lower density.
- We used water displacement to measure the volume of irregularly shaped objects (rock, key, sharpener).
- Always remember: Density = Mass ÷ Volume, and units are typically g/mL or g/cm³.

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