Monday, August 24, 2020



Upthrust is a force felt by an object either immersed or floated on liquid. Upthrust depends upon density of liquid and cross section area of object that is on contact with liquid.

Q1. Why an egg sinks on tap water but floats on salt water?

Ans: Egg sinks on tap water because density of tap water is low and provides little upthrust upon egg which is less than weight of egg and hence egg sinks. But concentrated salt water has enough density to provide upthrust that is equal to weight of egg and hence egg floats on salt water.

Q2. A nail sinks on water but ship made of metal floats with heavy load why?

Ans: In general nail has higher density than water and sinks on water but ship made of same material has large area of contact with water on which water exerts large upthrust and hence floats with heavy load.

Q3. A ship can carry more load on ocean than on river why? (Left for student, plz answer in comment)


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