The rate of doing work, or of transforming energy, can be measured in
A) joules.
B) newtons.
C) kilowatt-hours.
D) Calories.
E) watts.
E
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The tank of a certain car holds 16 gallons of gasoline. (1.00 gal = 3.785 L) (a) How many liters of gasoline does this tank hold? (b) How many kilometers can the car travel on one tank if it gets 25 miles per gallon?
What will be an ideal response?
What phenomenon is created by two tuning forks, side by side, emitting frequencies, which differ by only a small amount?
a. resonance b. interference c. the Doppler effect d. beats
The image formed in a plane mirror is
A) at the same distance in front of the mirror as the object is in front of the mirror. B) at the same distance behind the mirror as the object is in front of the mirror. C) at a shorter distance behind the mirror than the distance the object is in front of the mirror. D) a real image behind the mirror. E) at a larger distance behind the mirror than the distance the object is in front of the mirror.
Air at 16°C and atmospheric pressure enters a 1.25-cm-ID tube at 30 m/s. For an average wall temperature of 100°C, determine the discharge temperature of the air and the pressure drop if the pipe is (a) 10-cm-long and (b) 102-cm-long.
GIVEN
• Atmospheric air flowing through a tube
• Entering air temperature (Tb,in) = 16°C
• Tube inside diameter (D) = 1.25 cm = 0.0125 m
• Air velocity (V) = 30 m/s
• Average wall surface temperature (Ts) = 100°C
FIND
The discharge temperature (Tb,out) and the pressure drop (?p) if the pipe length (L) is
(a) 10 cm (0.1 m) (b) 102 cm (1.02 m)
ASSUMPTIONS
• Steady state
• The tube is smooth
SKETCH
for dry air at the entering bulk temperature of 16°C
Density (?) = 1.182 kg/m3
Thermal conductivity (k) = 0.0248 W/(m K)
Kinematic viscosity (?) = 15.3 × 10–6 m2/s
Prandtl number (Pr) = 0.71
Specific heat (c) = 1012 J/(kg K)