Hot Air Balloon
- Hot air in the balloon has lower density than the surrounding air.
- As a result, when the buoyant force produced is higher than the weight of the balloon, the balloon will start rising up.
- The altitude of the balloon can be controlled by varying the temperature of the air in the balloon.
A submarine use ballask tank to control its movement up and down.
To get submerge, water is pumped into the ballast tank to increase the weight of the submarine.
To surface, the water is pumped out to reduce the weight of the submarine.
Q & A
Q: The diagram shows a picture of a hydrometer. What is the function of the lead shot at the bottom of the hydrometer?
To lower down the centre of gravity of the hydrometer. The hydrometer will topple if the centre gravity of the hydrometer is above the surface of the liquid.