Aptitude Test Problems in Physics Science for Everyone by S Krotov ( PDFDrive.com )

Fig. 196

a—
h 2 + hi •

whence

g (h 2 —h 1 )

206 Aptitude Test Problems in Physics

According to the law of communicating vessels, the
surfaces of the liquid in the arms of the manometer
belong to the above-mentioned inclined plane

(Fig. 196). It follows from geometrical considera-

tions that

tan

h (^2) — hi
q—
hz+ (^) hi
1.113. The air layer of thickness Ax at a distance x
from the front of the cabin experiences the force of
pressure
[P-(x^ Ax) — p (x)] S,
where S is the cross-sectional area of the cabin.
Since air is at rest relative to the cabin, the equa-
tion of motion for the mass of air under considera-
tion has the form
pS Axa = [p (x Al) — p (x)1 S.
Making Ox tend to zero, we obtain
dp
=pa,
dx
whence
P (z) = Par.