Question

An air bubble raising from the bottom to the surface of a lake doubles its diameter. If the atmospheric pressure is 76 cm of Hg, What is the depth of water
in the lake?
only answer please

Answer 1

Solution

As volume of air bubble becomes double on reaching the surface of lake, hence its pressure becomes half. Since on the lake, the pressure is equal to the atmospheric pressure, hence the pressure of air inside the bubble at the depth of lake = 2 atmospheric pressure = atmospheric pressure + pressure due to column of water h. thus

2×76cmofHg=76cmofHg+hcm of wateror76 cm of Hg = h cmofwaterofDepthoflake= 76 cm of Hg=76 xx 13.6 cm of water=1033.6 cm = 10.34 m`