Density, buoyancy, and water displacement quiz for Grade 8 science

📚 Quick Study Guide

• ⚖️ Density: Density is mass per unit volume. The formula is: $Density = \frac{Mass}{Volume}$
• 📏 Volume: Volume is the amount of space an object occupies. For regular shapes, you can calculate it (e.g., $Volume_{cube} = side^3$). For irregular shapes, use water displacement.
• 💧 Water Displacement: The volume of water displaced by an object is equal to the volume of the object.
• 🎈 Buoyancy: Buoyancy is the upward force exerted by a fluid that opposes the weight of an immersed object.
• ⚓ Archimedes' Principle: The buoyant force on an object is equal to the weight of the fluid displaced by the object.
• 🌊 Floating vs. Sinking: An object floats if its density is less than the density of the fluid. It sinks if its density is greater. If the densities are equal, the object neither sinks nor floats (it is neutrally buoyant).

🧪 Practice Quiz

1. What is the formula for calculating density?
   1. $Density = Mass \times Volume$
   2. $Density = \frac{Volume}{Mass}$
   3. $Density = Mass + Volume$
   4. $Density = \frac{Mass}{Volume}$
2. An object has a mass of 60g and a volume of 20 $cm^3$. What is its density?
   1. 0.3 g/$cm^3$
   2. 3 g/$cm^3$
   3. 1200 g/$cm^3$
   4. 40 g/$cm^3$
3. What principle explains why objects float?
   1. Newton's First Law
   2. Archimedes' Principle
   3. The Law of Conservation of Mass
   4. The Pythagorean Theorem
4. If an object displaces 50 mL of water, what is the volume of the object?
   1. 25 mL
   2. 100 mL
   3. 50 mL
   4. It cannot be determined
5. An object will float in water if its density is:
   1. Greater than the density of water
   2. Equal to the density of water
   3. Less than the density of water
   4. Always the same, regardless of water density
6. What is buoyancy?
   1. The weight of an object
   2. The downward force on an object
   3. The upward force exerted by a fluid
   4. The mass of an object
7. A block of wood has a density of 0.6 g/$cm^3$. Will it float or sink in water (density 1 g/$cm^3$)?
   1. Sink
   2. Float
   3. Neither float nor sink
   4. It cannot be determined