Ships float submarines sink

Answer 1

Wrong!!!!

Ships float, and submarines also float.

However, submarines have special buoyancy tanks, which are filled with sea-water, which then makes then sink. The air in these tanks is removed by a vacuum, out into compressed air cylinders. , this allows water to enter and hence the submarine sinks. To make the submarine re-surface, the compressed air in the compression tanks is blown back into the buoyancy tanks, thereby pushing out the sea-water, hence the submarine re-surfaces(floats).

Remember the Archimedian Principle.

'The weight of a body immersed in a fluid is equal to the weight of the fluid displaced'.

As an experiment to yourself, obtain a spring balance, an house brick and a tanks of water.

Attach the brick to the spring balance, with a piece of string, and note the weight in air. Now keeping the brick attached to the spring balance lower it into the water of the water tank, and note the new less weight. The difference in the weight is the weight of the water displaced by the brick.

Hence Archimedes principle and the reason why ships and submarines can float, because the displace less water.

Answer 2

Submarines can go downward because they flood their buoyancy tanks with water. This reduces the buoyancy of the sub, allowing it to go down. To rise again, the water is pumped out of these tanks.