Question

A Piece of gold alluminium alloy weighs 49N. When suspended from a spring balance and Submerged in water it weighs 39.2N What is the weight of Gold in the alloy if the specific gravity of Gold is 19.3 and that if aluminium is 2.5?​

Answer 1

We can start by calculating the volume of the gold in the alloy and then use its density to determine its weight.

First, let's find the weight of the alloy when it's not submerged in water:

Weight of alloy = 49 N

Next, let's find the buoyant force, which is equal to the weight of the water that's displaced by the object:

Buoyant force = weight of water displaced = 39.2 N

So, the weight of the object in water can be calculated as:

Weight in water = Weight of alloy - Buoyant force = 49 N - 39.2 N = 9.8 N

Next, let's calculate the volume of the object using its density:

Volume = Weight in water / (Density of alloy - Density of water)

Since the density of water is 1 g/cm^3, we can simplify the equation as:

Volume = 9.8 N / (Density of alloy - 1)

Since the specific gravity of Aluminium is 2.5, its density can be calculated as:

Density of Aluminium = 2.5 * Density of water = 2.5 * 1 g/cm^3 = 2.5 g/cm^3

So, the volume of the object can be calculated as:

Volume = 9.8 N / (2.5 g/cm^3 - 1 g/cm^3) = 9.8 N / 1.5 g/cm^