A spaceship leaves Earth at 70.0% the speed of light. How fast must the spacecraft launch a shuttlecraft with respect to the ship so that it appears, from Earth, to be moving 98.7% the speed of light away
A) 0.928c
B) 0.966c
C) 0.987c
D) 0.972c
E) 0.911c
A
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A person standing in the street is unaware of a bird dropping that is falling from a point directly above him with increasing velocity. If the dropping were producing sound of a fixed frequency, as it approaches the person would hear the sound
a. drop in frequency. b. stay at the same frequency. c. increase in frequency. d. decrease in loudness. e. stay at the same loudness.
The SAE J-1930 standardized name for the sensor that measures the temperature of the air being drawn into the engine is called a(an) ________.
A. Air temperature sensor (ATS) B. Air charge temperature (ACT) sensor C. Manifold air temperature (MAT) sensor D. Intake air temperature sensor (IAT)
Mercury at an inlet bulk temperature of 90°C flows through a 1.2-cm-ID tube at a flow rate of 4535 kg/h. This tube is part of a nuclear reactor in which heat can be generated uniformly at any desired rate by adjusting the neutron flux level. Determine the length of tube required to raise the bulk temperature of the mercury to 230°C without generating any mercury vapor, and determine the corresponding heat flux. The boiling point of mercury is 355°C.
GIVEN
• Mercury flow in a tube
• Inlet bulk temperature (Tb,in) = 90°C
• Inside tube diameter (D) = 1.2 cm = 0.012 m
• Flow rate (m ) = 4535 kg/h = 1.26 kg/s
• Outlet bulk temperature (Tb,out) = 230°C
• Boiling point of mercury = 355°C
FIND
(a) The length of tube (L) required to obtain Tb,out without generating mercury vapor
(b) The corresponding heat flux (q/A)
ASSUMPTIONS
• Steady state
• Fully developed flow
SKETCH
PROPERTIES AND CONSTANTS
for mercury at the average bulk temperature of 160°C
Density (?) = 13,240 kg/m3
Thermal conductivity (k) 11.66 W/(m K)
Absolute viscosity (?) = 11.16 × 10–4 (Ns)/m2
Prandtl number (Pr) = 0.0130
Specific heat (c) = 140.6 J/(kg K)
Marshmallows in a vacuum become
A) larger. B) smaller. C) flat. D) a hollow shell. E) none of the above