As measured from the Earth, a spacecraft is moving at speed 0.80c toward a second spacecraft moving at speed 0.60c back toward the first spacecraft. What is the speed of the first spacecraft as viewed from the second spacecraft?
a. 0.81c b. 0.95c
c. 0.38c d. 0.20c
b
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For an observer on Uranus, the ecliptic passes only a few degrees from the celestial poles
Indicate whether the statement is true or false
Green light has a shorter wavelength than orange light. In a 5-inch telescope, green light will
A) come to the same exact focus as orange light. B) reduce the effects of atmospheric turbulence. C) provide worse angular resolution than orange light. D) provide better angular resolution than orange light. E) allow dimmer stars to be observed.
A flask half filled with water is on a weighing scale. If you suspend a stone by a string into the water the scale reading will be
A) less. B) the same. C) greater.
Which of these statements correctly compares battery cells in series with the cells in parallel?
a. When battery cells are in series, the voltage stays the same but the cells last longer. b. When battery cells are in parallel, the voltage increases, but the cells last the same amount of time. c. When battery cells are in series, the voltage increases and the cells last longer. d. When battery cells are in parallel, the voltage stays the same and the cells last longer. e. When battery cells are in parallel the voltage is the same and they last just as long as when the cells are in series.