1. How does the Buoyancy Force change with depth ? or How do fish ever reach the bottom of the sea ? Swim bladder – A gas pocket which can be controlled to keep the fish at a constant depth

2. Changing the depth 5N 10 N 15 N 20 N BF=5N up

3. Conclusion The buoyancy force does not change with depth. The difference between the top force and the bottom force is always the same no matter what the depth. So fish have no problem reaching the bottom. They just die!

4. Just joking ! They can control their buoyancy by expanding the amount of gas in their swim bladders. This increases their volume and so increases the buoyancy force.