Notes
• Office Hours: M, T 4-6+pm, NSH 414
• Help Sessions: M,T, 6:30-8:30pm
– O’Shaughnessy 106
U-Tubes:
• Which fluid is more dense?
• The pressure at A is
a) greater than
b) less than
c) the same as
the pressure at B.
A rectangular dam 30 meters wide supports a body of
water of depth 25 meters. Find the total horizontal force
on the dam.
The Atmosphere
Atmospheric pressure at sea level is approximately
1.1×105 Pa. How far under water would we have to go
to experience the same pressure? Assume there is no
atmosphere above the water.
Pascal’s Principle
• Pressure applied to an enclosed fluid is transmitted
undiminished
di i i h d to
t every portion
ti off the
th fluid
fl id andd to
t the
th
walls of the containing vessel.
• basis of all hydraulic systems
The Hydraulic Lever
In the 17th century, Pascal performed the following experiment.
A wine barrel filled with water was coupled to a long tube. Water
was added to the tube until the barrel burst. The radius of the
barrel’ss lid was 20 cm,
barrel
cm and the tube of water was 12m high.
high
(a) Calculate the force on the lid due to the column of water.
(b) If the tube had an inner radius of 3.0mm,
3 0mm what was the mass
of the water responsible for bursting the barrel?
Archimedes’ Principle
• A body wholly or partially immersed in a fluid is
b
buoyed
d up by
b a force
f
equall in
i magnitude
it d to
t the
th
weight of the fluid displaced by the body.
“Archimedes Tomb”, Syracuse, Sicily
The density of ice is approximately 917 kg/m3. What
fraction of the total volume is the proverbial “tip of the
iceberg” that one can see floating above the ocean?
A boat loaded with a ton of sand sits in a closed lock on
the Erie Canal. All of a sudden, the sand accidentally
spills into the bottom of the lock, with the boat
remaining safely afloat. After the accident, the water
level in the lock
a) rises
b) descends
c) stays the same
Several ice cubes float in a glass of water. After the ice
melts, the water level in the glass
a)) rises
ses
b) descends
c) stays
sta s the same