Quiz 1
1) What of the following is a WRONG statement.
A)
When a load of steel is dropped from a boat floating in a lake, the water level in the lake
falls.
B)
An ice cube with a piece of cork frozen into it is floating in a glass of water. When the
ice melts the water level falls.
C)
An ice cube with a steel nut frozen into it is floating in a glass of water. When the ice
melts the water level falls.
D)
When an ice cube floating in a glass of water melts, the level of water remains the same.
2) What of the following is a WRONG statement.
A)
The equation vA = const is only valid under the conditions of conservation of mass and
incompressibility of the fluid.
B)
A steady flow implies that the velocity does not change in time, but might still change
along streamlines.
C)
Positioning of the center of buoyancy of a boat below its center of gravity guarantees
stability of the boat.
D)
Variation of hydrostatic pressure with the height/depth is proportional to the density of
the fluid.
3) A manual hydraulic lift has a 45cmdiameter piston supporting the load, and it can go up by a
maximal height of 80 cm. The maximal load it can support is 500 kg. The manually driven piston has a
diameter of 8 cm. What is the force one needs to apply to the manually driven piston to lift the maximal
load, if there is no friction.
A) 160 N
B) 870 N
C) 500 N
D) 16 N
4) A balloon filled with Hydrogen (density 0.09 kg/m3) has a volume of 120 m3. The mass of the
balloon, excluding the gas inside, is 12 kg. What is the maximal load the balloon can lift, if the density
of air is 1.20 kg/m3?
A) 135 kg
B) 120 kg
C) 1210 kg
D) 142 kg
5) On land, the most massive piece of a material you can carry is 35 kg. The heaviest piece of the same
material you can carry under water has a mass of 42.5 kg. What is the density of the material. The
density of water is 1000 kg/m3.
A) 7500 kg/m3
B) 1200 kg/m3
C) 5500 kg/m3
D) 4500 kg/m3
6) A venturi is constructed of a pipe with a diameter of 14 cm and a throat diameter of 2.8 cm. Water in
the pipe has a pressure of 2 atm and it flows with a velocity of 0.7 m/s. What is the pressure in the
throat?
A) 1.6 atm
B) 3.5 atm
C) 0.5 atm
D) 2.4 atm
7) Consider a thinwall tube with a length of 8 m and with a crosssection having a shape of a square
with a side of 1.5 m. The pressure inside the tube is 0.65 atm. The pressure outside of the tube is 0.35
atm. (1 atm = 105kPa). What is the net force tending to separate one half of the tube from the other
half, in Newtons?
A) 2.4x10
6
B) 3.6 x10
5
C) 7.2 x10
5
D) 1.2 x10
6
8) An open jar contains a 12 cm of sea water (density 1.03 g/cm3) and 24 cm of oil (density 0.82
g/cm3) above the water. The pressure of the atmosphere is 1.03 x10
5
Pa. What is the absolute pressure
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A) 1.06 x10
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 Spring '10
 Whitley
 Physics, Light, Wavelength, wrong statement

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