A student weighing 200 N climbed a flight of stairs 9.0 m high in 4 s. How much work was done by the student?
a. 1800 J
b. 800 J
c. 1800 W
d. 800 W
e. 50 W
Answer: a. 1800 J
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A system of 3 masses is located as follows: m1 = m0 at (0, L), m2 = 2m0 at the origin, and m3 = 3m0 at (3L, 0). Where is the center of mass of these masses
A. L/6, 3L/2 B. 5L/6, 3L/2 C. 2L/13, 5L/6 D. 3L/2, L/6
Do you remember how we do measure distances to stars?
A: inverse square law B: p-p chain C: parallax D: measure sizes E: none of the above
Statistical evidence
a. can be used to draw conclusions about a specific cases. b. is applicable to classes of objects where only a few objects from the class have been studied. c. allows scientists to determine the mechanism that produces the dust ring in Centaurus A. d. allows scientists to deduce general characteristics about a class of objects with similar properties. e. provides insight into the behavior of an individual object based on careful observations of it.
What is the difference between an emission and a reflection nebula?
A. Generally, emission nebulas appear blue, and reflection nebulas look red. B. Emission nebulas contain many dying stars; reflection nebulas are stellar nurseries. C. Emission nebulas give off their own light; reflection nebulas reflect the light of nearby stars. D. All of these choices are correct.