How do submarines keep afloat?

Question

How do submarines keep afloat?

Answer 1

ballast tanks

Answer 2

All submarines have big tanks that they fill with sea water to make the sub heavier and therefore submerge.

When they want to surface they force the water out and replace it with air which makes the sub lighter.

Its all about balancing 10000tons of metal.

Answer 3

Magic!

Answer 4

Archimedes principal explains how boats float.

Answer 5

Buoyancy and ballast

Answer 6

By attaching empty Javex bottles to the front & back tips .

Answer 7

The same way the other boats do.

When they want to go above or below the sea level, they pump water out to go above and vice-versa to go down

Answer 8

very carefully!!!!!! it is the propertion of compression inside the sub. (eat fresh)

Answer 9

They dont always float sometimes they sink.

Answer 10

Submarines are made buoyant and add water to submerge, and to surface, air is pumped into the tanks to expell the air.

Answer 11

They will fill the ballast tanks with sea water if they want to dive.

When they want to go up to the surface they will use compressed air to empy the ballast tanks and this way they will get positive buoyancy and they will go up.

Answer 12

by keeping the water out...same as any boat

Answer 13

It's a simple matter of bouyancy.  If the submarine needs to dive, sea water is allowed into her ballast tanks.  These fill to a point where she has negative bouyancy, and thus dives.  

When she needs to surface, compressed air is used to expell the water, giving her positive bouyancy, and hence she returns to the surface.  

When submerged, dive planes (they look like small wings on the hull and conning tower of the submarine) are used to change depth.  The submarine flies through the water in a similar manner to an aeroplane flying through the air.

Answer 14

Air tanks Pull water in down she goes>Compressed air purges the water out up she goes>

Answer 15

Most of the time, they try not to.