Let's solve the problems step by step using the formula for density:
Formula:
\[
\text{Density} = \frac{\text{Mass}}{\text{Volume}}
\]
---
Problem 1:
You have a mineral with a volume of \(15 \, \text{cm}^3\) and a mass of \(45 \, \text{g}\). What is its density?
#### Solution:
\[
\text{Density} = \frac{\text{Mass}}{\text{Volume}} = \frac{45 \, \text{g}}{15 \, \text{cm}^3} = 3 \, \text{g/cm}^3
\]
#### Answer:
\[
\boxed{3}
\]
---
Problem 2:
You have a different mineral with a volume of \(15 \, \text{cm}^3\) and a mass of \(75 \, \text{g}\). What is its density?
#### Solution:
\[
\text{Density} = \frac{\text{Mass}}{\text{Volume}} = \frac{75 \, \text{g}}{15 \, \text{cm}^3} = 5 \, \text{g/cm}^3
\]
#### Answer:
\[
\boxed{5}
\]
---
Problem 3:
In the above two examples, which mineral is more dense?
#### Solution:
From Problem 1, the density of the first mineral is \(3 \, \text{g/cm}^3\).
From Problem 2, the density of the second mineral is \(5 \, \text{g/cm}^3\).
Since \(5 \, \text{g/cm}^3 > 3 \, \text{g/cm}^3\), the second mineral is more dense.
#### Answer:
\[
\boxed{\text{second, first}}
\]
---
Problem 4:
What is the density of a cube of sugar weighing \(12.8 \, \text{grams}\) measuring \(2 \, \text{cm}\) on a side?
#### Step 1: Calculate the volume of the cube.
The volume \(V\) of a cube is given by:
\[
V = \text{side}^3 = 2 \, \text{cm} \times 2 \, \text{cm} \times 2 \, \text{cm} = 8 \, \text{cm}^3
\]
#### Step 2: Use the density formula.
\[
\text{Density} = \frac{\text{Mass}}{\text{Volume}} = \frac{12.8 \, \text{g}}{8 \, \text{cm}^3} = 1.6 \, \text{g/cm}^3
\]
#### Answer:
\[
\boxed{1.6}
\]
---
Final Answers:
1. \(\boxed{3}\)
2. \(\boxed{5}\)
3. \(\boxed{\text{second, first}}\)
4. \(\boxed{1.6}\)
Parent Tip: Review the logic above to help your child master the concept of worksheet on density.