Introduction
When equal masses of different materials are weighed in water, the apparent weight of the objects will vary depending on their densities. This is because the buoyant force acting on an object in a fluid is directly proportional to the density of the fluid and the volume of the object.

Density and Buoyancy
Density is defined as the mass of an object per unit volume. The formula for density is given by:
Density = Mass / Volume

When an object is submerged in a fluid, it displaces an amount of fluid equal to its own volume. The buoyant force acting on the object is equal to the weight of the fluid displaced by the object. According to Archimedes' principle, the buoyant force is directed upward and is equal to the weight of the fluid displaced.

Effect of Density on Apparent Weight in Water
The apparent weight of an object in water is the difference between its actual weight and the buoyant force acting on it. If the density of the object is greater than the density of water, it will sink and have a negative apparent weight. If the density of the object is less than the density of water, it will float and have a positive apparent weight.

Comparison between Aluminium, Copper, and Gold
1. Aluminium:
- Density: The density of aluminium is about 2.7 g/cm³.
- Apparent weight in water: Since the density of aluminium is less than that of water (which is 1 g/cm³), the apparent weight of aluminium in water will be positive.

2. Copper:
- Density: The density of copper is about 8.96 g/cm³.
- Apparent weight in water: The density of copper is greater than that of water, so the apparent weight of copper in water will be negative.

3. Gold:
- Density: The density of gold is about 19.3 g/cm³.
- Apparent weight in water: The density of gold is much greater than that of water, so the apparent weight of gold in water will be significantly negative.

Conclusion
In conclusion, when equal masses of aluminium, copper, and gold are weighed in water, the aluminium will have a positive apparent weight, the copper will have a negative apparent weight, and the gold will have a significantly negative apparent weight. This is due to the differences in density between the materials and water.

Copper