🔹 Subjective Questions (Click to View Answers)
1. How can we measure the volume of milk contained in a cup?
We can measure it using a measuring cylinder or measuring cup.
Pour the milk into the measuring cylinder and note the reading.
2. Describe a method to measure the area of the following:
a. A regular shaped object
Measure its dimensions (length, breadth, radius, etc.) and use the appropriate formula.
Example: Area = length × breadth.
Example: Area = length × breadth.
b. An irregular shaped object
Place the object on graph paper and trace its outline. Count full squares and include squares that are half or more than half.
Total area = sum of these squares in cm².
Total area = sum of these squares in cm².
3. Explain the procedure to determine the density of an irregular solid.
- Measure mass using a balance.
- Note initial water level in measuring cylinder.
- Immerse the solid and note final level.
- Volume = Final − Initial (water displacement method).
- Density = Mass / Volume.
4. Distinguish between density and relative density.
| Density | Relative Density |
|---|---|
| Mass per unit volume | Ratio of density of substance to water |
| Formula: Mass / Volume | Ratio of densities |
| Has unit (kg/m³ or g/cm³) | No unit |
| Absolute value | Comparative value |
🔢 Numericals (Step-by-Step Solutions)
1. The radius of a circle is 7 mm. Find its area.
Formula: Area = Ï€r²
Ï€ = 22/7, r = 7 mm
Area = (22/7) × 7 × 7
Area = 154 mm²
2. A metallic sphere weighs 450 g. Volume = 50 cm³. Find density.
Formula: Density = Mass / Volume
Mass = 450 g, Volume = 50 cm³
Density = 450 / 50
Density = 9 g/cm³
3. Convert 27 km/h into m/s.
Conversion formula: km/h × (5/18)
Speed = 27 × (5/18)
= (27 × 5) / 18
Speed = 7.5 m/s
