What is the composition of the gas clouds (nebulae) we see in space?
a. about half hydrogen and helium, half heavier elements (iron, carbon, silicon, etc.)
b. about 98% hydrogen and helium, and 2% heavier elements
c. about 2% hydrogen and helium, and 98% heavier elements
Answer: b. about 98% hydrogen and helium, and 2% heavier elements
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Viscosity: A fluid is flowing with an average speed of 1.5 m/s through a tube that has a radius of 2.0 mm and is 18 cm long. The drop in pressure is 967 Pa. What is the viscosity of the fluid?
A. 0.0018 N ? s/m2 B. 0.0056 N ? s/m2 C. 0.028 N ? s/m2 D. 0.013 N ? s/m2 E. 0.0034 N ? s/m2
Notice the numbered points on this photo of the Gemini North reflecting telescope. Where is the secondary mirror located?
A) Point 1 B) Point 2 C) Point 3 D) Point 4
Why do most jovian moons show the same face to their planet?
A) because the moons once had atmospheres B) because the entire solar nebula rotated in the same direction C) because of the law of conservation of angular momentum D) because of tidal forces acting on the moons E) No one knows; it is still a mystery.
An unstable particle initially at rest breaks up into two fragments. The mass of one fragment is 1.75 × 10^–28 kg and the mass of the other fragment is 1.25 × 10^–27 kg. The lighter fragment has a speed of speed 0.850c. What is the speed of the heavier fragment?
a. 0.229c b. 0.119c c. 0.127c d. 0.220c