A) An object weighs 40 g in air and has a volume of 8.0 cm3. What will be its apparent weight when immersed in water?
To avoid confusion between grams and the acceleration due to gravity, I will assign
Weight of an object in air is
When immersed in water, the object will displace
The density of water is
Therefore the mass of the displaced water will be
The weight of the displaced water is
Therefore the object has a upward buoyant force equal to
The weight of the object in air (a downward force) and the buoyant force (an upward force) are both components of the apparent weight in water. Therefore we will have to subtract the 2 forces.
Or, using the terminology the question was asked with:
I hope this helps,