Bukhovtsev-et-al-Problems-in-Elementary-Physics

MECHANICS 57
243. A tube floats vertically in water (Fig. 98). The portion
of the tube protruding from the water is h = 5 em. Oil with a
specific weight of y =0.9 gf/cm 8 is poured into the tube. What
length can the tube have so that it can be completely filled
with oil?
244. A vessel with water falls with an acceleration a < g.
How does the pressure p in the vessel change with depth?
245. A vessel with a body Boating in it falls with an acceleration
a < g. Will the body rise to the surface?
246. A cart supports a cubic tank filled with water up to its
top (Fig. 99). The cart moves with a constant acceleration a.
Determine the pressure at point A which is at a depth h and a
distance I from the front wall, if the tank is tightly closed with
a lid. In uniform motion the lid does not exert any pressureon
the water.
247. A rubber ball with a mass m and a radius R is submer..
ged into water to a depth h and released. What height will the
ban jump up to above the surface of the water? Disregard the
resistance of the water and the air.
248. Mercury is poured into two communicating cylindrical
vessels, and water is poured in above it. The level of the water
is the same in both vessels. Will the level of the water and the
mercury be the same if a piece of wood is dropped into one
vessel and some water equal in weight to this piece is added to
the other? Consider cases when the cross sections of the vessels
are the same or different.
:t:::====;7
=--~ =-.J.:--w---.:=
,--I -:c- 1--
=-F~~~
-- L--~ ......._ ..;7 ~ _
Fig. 97 Fig. 98