Page 36 - Pressure 10 class

Some give reasons based on Upthrust

4. It is easier to pull a bucket of water from a well until it is

inside the water but difficult When it is out of water, why?

Ans; water exerts upthrust on the bucket which reduces weight of

the bucket. Outside water there is very less upthrust of air. Thus,

the force required to pull a bucket when immersed in water is

less than that required to pull when it is out of water.

5. An iron ball sinks in water but floats in mercury, why?

Ans; An iron ball has more density than water so it sinks in water

but it floats in mercury because it has less density than mercury.

6. What is the difference between a boat floating in fresh river water

and sea water?

Ans; A boat sinks more in fresh water to displace more amount of

water to float because fresh water has less density .But sea water

has more density due to the pressure of salt ,so the boat sinks less .

July 30, 2020 Taranath Baral/GC Shiba/Suraj Thapaliya 36