Water is denser than air. As the water is pumped out, air replaces the space that was occupied by the water. Therefore, the total density of the sub decreases. The above answer is correct. Here is a little more detail.
As you may be aware density is a function of mass and of volume. It's mass per unit of volume. If you had a pan full of water and a similar pan which was empty, the water filled pan would weigh more, though the overall volume would be the same. Hence the density would be greater.
When the submarine 'pumps out' the water it is replaced by air. Because air is less dense than water, it reduces the overall density of the vessel. Consider that the submarine is a vessel, as in a ship, and also a vessel, as in something that holds something else, like a cooking vessel. The submarine is a closed vessel; it has a fixed volume set by the hull. But by pumping water into or out of its internal tanks, it can change its total mass. If it pumps water in, it is increasing its total mass, and this will increase its density (as the volume stays the same). Pumping water out decreases the submarine's total mass, and its density will go down.
Because the tanks are filled with air afterwards. Air has a lower density than water.
because of density
It doesn't pump air out; it forces water out of its ballast tanks to increase its buoyancy.
Yes, when a submarine boat pumps water out of its flotation (not floatation) tanks, the submarine should rise.
The water is replaced with air which is not as heavy as water for the same volume.
Density = mass / volume. If the mass decreases, the density decreases.
Because the tanks are filled with air afterwards. Air has a lower density than water.
Because the tanks are filled with air afterwards. Air has a lower density than water.
Density = mass / volume. If the mass decreases, the density decreases.
Density = mass / volume. If the mass decreases, the density decreases.
To rise again, the submarine's weight must be decreased. Air is pumped into the ballast tanks to force the water out. The buoyant force acting on the submarine now exceeds the submarine's weight. With positive buoyancy, the submarine rises. The less weight an object has the more its density decreases. Hope that kinda helps?
Because the tanks are filled with air afterwards. Air has a lower density than water.