Why do the spectra of stars differ, if they are all chiefly hydrogen and helium?
What will be an ideal response?
Temperature differences causes some elements to be more prominent than others; for instance, helium shows up well in the hottest O and B stars, while more reactive metal atoms show up better at lower temperatures, even combining to make molecules the coolest K and M stars.
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Explain the process through which kinetic energy is conserved in an elastic collision
What will be an ideal response?
A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v0 and there is no air. If the 10-kg rock reaches a maximum height h, what maximum height will the 20-kg ball reach?
A) h/4 B) h/2 C) h D) 2h E) 4h
An electron moves with a speed of 5.0 × 104 m/s perpendicular to a uniform magnetic field of magnitude 0.20 T. What is the magnitude of the magnetic force on the electron? (e = 1.60 × 10-19 C)
A) 2.6 × 10-24 N B) 5 × 10-20 N C) 4.4 × 10-14 N D) 1.6 × 10-15 N E) zero
The total electromagnetic power emitted by the sun is 3.8 ×1026 W. What is the radiation pressure it exerts on the perfectly absorbing surface of a satellite near the orbit of Mercury,
which is 5.8 × 1010 m from the sun? The radiation strikes the surface of the satellite perpendicular to the surface. (c = 3.0 × 108 m/s)