1.請簡單介紹甚麼是浮力。
Upthrust (浮力) is an vetically upward force experienced by a body when it is totally or partially immersed in a fluid.
Upthrust arises due to the difference in fluid pressure at the top and bottom of the body.
2. 船為什麼能浮在水面。
According to the principle of floatation, the upthrust is equal to the weight of fluid displaced.
Ships have vast empty space in the hull. This empty space displaces quite large an amount of water, thus increasing the upthrust. When the upthrust balances the weight of the ship, the ship floats.
3. 假如在一杯水中放入一只雞蛋,為什麼在加入適量的鹽後,能使雞蛋浮在水面。
The adding of salt increases the magnitude of upthrust on a body.
Salt water has a larger densith than pure water. Thus, for a fixed volume of water displaced, the weight of salt water weights more than pure water. That is to say, the upthrust (which equals to the weight of water dispalced) becomes larger, and which is sufficient to float the egg.