ur answer iss...
A submarine sinks by taking water into its buoyancy tanks. Once submerged, the upthrust is unchanged, but the weight of the submarine increases with the inflow of water and it sinks faster. Compressed air is used to blow water out of the tanks when it has to resurface.
(An atomic submarine. This remains underwater for weeks without surfacing).
- Balloons filled with hot air or hydrogen, weigh less than weight of cold air that it displaces. Therefore, the upthrust is greater than its weight and the resultant upward force on the balloon, causes it to rise.
- Hydrometer is used to measure relative density of a liquid. It consists of a weighted sealed glass tube and a scale and when placed in the liquid, the scale reads the level of the liquid surface. In a denser liquid, the scale floats since less liquid is displaced. The weight of the displaced liquid is equal to its own weight, the number on the scale therefore, increases downwards. This method is use to check the state of a car battery. In a fully charged medium, the R.D of the acid should be 1.25 and recharging is required when reading is less than 1.8.
hope u got the answer
