As measured from the Earth, a spacecraft is moving at speed 0.80c toward another spacecraft moving at speed 0.60c in the same direction, i.e., the first spacecraft is catching up with the second spacecraft. What is the speed of the first spacecraft as viewed from the second spacecraft?
a. 0.38c
c. –0.38c
b. –0.20c
d. not given
A
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A heat pipe having an effective length of 80 cm uses methanol as the working fluid. At an operating temperature of 20ºC the methanol flow rate is 12 mg/s, and the heat pipe uses an axially grooved wick arrangement with 60 equally spaced 2.1-mm-deep grooves. Determine the width of the grooves.
What will be an ideal response?
Calculate (0.83 + 0.049)(4.4 × 10^3), keeping only significant figures
a. 3 900 b. 3 868 c. 3 886 d. 3 644 e. 4 000
What is the purpose of adaptive optics?
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The reference point for latitude
What will be an ideal response?