PHYS 2C, W 2006
FINAL EXAM
Version
D
Name___________________________________
Code______________
MULTIPLE CHOICE.
Choose the one alternative that best completes the statement or answers the question
1) 600 ft tall Hoover Dam is made to withstand the pressure due to the water of Lake Mead, which is
115 miles long. How would that pressure change if Lake Mead is replaced by "Lake Mudd" of the
same depth but only 115 inches long (see figure)? 1 mi
=
1.609 km, 1 in
=
2.52 cm.
A) Decrease 644 times
B) Decrease 115000 times
C) Remain the same
D) Decrease 64389 times
1)
2) A cylindrical tank 24.0 cm in diameter is filled with water to a height of 20.0 cm. A small hole is
made in the bottom of the tank. Find the speed at which the water leaks through the hole.
A) 1.1 m/s
B) 3.92 m/s
C) 1.98 m/s
D) 5.1 m/s
2)
3) A 621.0

g iron meteor impacts the earth at a speed of 1922 m/s. If its kinetic energy goes entirely
into heating of the meteorite, what will the resultant temperature rise be? The specific heat of iron is
113 cal/kg
·
°C. 1 cal
=
4.184 J.
A) 3910° C
B) 16,300° C
C) 6.30° C
D) 2,430,000° C
3)
4) Warm blooded aquatic animals (body temperature 37° C) survive in cold water (4° C) due to
thermal insulation provided by blubber

an organic material of thermal conductivity 0.1 W/m
·
K.
The metabolic heat production rate Q of all animals is known to universally obey the approximate
law Q
=
560 W x (V / m
3
)
3/4
, where V is the volume of an animal. Suppose a whale can be
approximated by a sphere of radius R
=
3 m. What minimal thickness of blubber would keep it
warm? Volume of a sphere is (4 π / 3) R
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 Winter '05
 wurthmeir
 Photographic lens, Lake Mead

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