[masraum]

Originally Posted by hbueno

Force (weight) is a vector quantity, meaning it has magnitude and direction. If gravity and buoyancy are acting on a mass, the net force (weight) is the vector addition of the two forces.

Exactly.

That leads to the question that is "Is weight the net force acting on the mass, or is it only the force due to gravity?"

If you look in Webster, it lists the first definition of weight as being something measured by weighing. And then if you look up the verb weigh, it says to measure something as by a scale. So, to me that says that weigh can be how something is measured on a scale which would make it a net force. But, I also absolutely agree that in a physics class at a basic level, weight would be considered the result of one force acting on the mass due to gravity, not the net force.

Using those two definitions, an item that sinks in the ocean is going to weight less in the ocean than in air due to bouyancy (first definition, net force). But also, an item will weigh the same whether it's in the water or not, with the only way to change that weight to determine the exact gravitational constant at the particular point where the item is in reference to earth (second definition, force due to gravity only).