The fact that a spacecraft does not have to fire its engines continuously as it moves in space is a consequence of
a. Snell's law.
b. Newton's Third Law of motion.
c. Einstein's theory of relativity.
d. Newton's First Law of motion.
e. Newton's Second Law of motion.
D
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Northern Hemisphere winters are colder than Northern Hemisphere summers because
a. Earth is closer to the sun during the summer than it is during the winter. b. the snow that falls in the northern latitudes cools Earth during the winter. c. the light from the sun shines more directly on the Northern Hemisphere during the summer. d. the period of sunlight is longer during the summer than during the winter. e. c and d
In Physical Geography the processes talked about are fundamentally products of energy from
What will be an ideal response?
A horizontally-projected beam of electrons travelling at 55 km/s travels between two parallel plates separated by 7.4 cm, and 12 cm long, between which there is an electric field of 7.2 mV/m upward. If the beam enters the region at a height of 3.7 cm above the lower plate, at what height above the lower plate is the beam when it exits? The electron mass is 
A. 0.9 cm B. 2.3 cm C. 5.1 cm D. 4.6 cm
According to the inverse square law of light, how will the apparent brightness of an object change if its distance to us triples?
A) Its apparent brightness will decrease by a factor of 3. B) Its apparent brightness will increase by a factor of 9. C) Its apparent brightness will increase by a factor of 3. D) Its apparent brightness will decrease by a factor of 9.