Page 35 - Pressure 10 class
P. 35
Some give reasons based on Upthrust
1. It is easier to swim in the sea water, why?
Ans; Upthrust is directly proportional to the density of the liquid. Sea water has a
greater density than river water. Thus, upthrust experienced by a swimmer in
sea water is comparatively more than in river water. So, it is much easier to
swim in the sea water.
2. The weight of an object in air is more than that in water. Why?
Ans; Upthrust is directly proportional to the density of the liquid. Density of air is
less than that of water. The upthrust due to air is negligible in comparison to
the upthrust due to water. S o, the weight of an object in air is more than that
in water.
3.An egg sinks in pure water but floats in salt solution, why?
Ans;. The density of water is less than the density of the
salt Solution. As, we know, upthrust is directly proportional
to the density of liquid.(i.e Uα d ) so, salt solution exerts more
upthrust on the egg where as water exerts less upthrust on
the egg. Therefore, an egg floats in salts solution and sinks in pure water.
July 30, 2020 Taranath Baral/GC Shiba/Suraj Thapaliya 35
