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7. What happens when ship enters a river from the sea?

Ans; When a ship enters a river from the sea it will sink more then the sea . It

is because salty water of the sea has more density and provides more

upthrust. But fresh river water has less density and provides least

upthrust. So, a ship sinks more to push more weight of water to bloat.

8. When we press ball inside water it tries to come upwards, why?

Ans; A ball always tries to rise upward when pressed

inside the water because the upthrust acting in the ball

by water is greater than weight of the ball . Hence, the

ball can easily displace water equal to its weight.

9. One has difficulty breathing in deep well while cleaning it, why?

Ans ; We know that the density of carbon dioxide gas is more than

the density of air. Due to this, carbon dioxide accumulates at

bottom of a well. Hence, one has difficulty breathing in deep well while

cleaning it.

July 30, 2020 Taranath Baral/GC Shiba/Suraj Thapaliya 37