What factors would determine that we live in a matter-dominated universe?
What will be an ideal response?
The density of matter can be approximately determined through observation; it's about 10-27 kg/m3. The microwave background (which is more abundant than starlight) can be converted into an equivalent amount of matter using E = mc2. The result is a density of 10-31 kg/m3. Since this is much lower than the matter density, we conclude we live in a matter dominated universe.
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During a reaction, 1.7 × 10-4 J of energy is released. What change of mass would cause this?
A) 5.1 × 10-4 kg B) 4.3 × 10-11 kg C) 1.5 × 10-13 kg D) 4.8 × 10-18 kg E) 1.9 × 10-21 kg
Large sunspots are larger than our whole planet
Indicate whether the statement is true or false
If the Moon were four times as massive but twice as far from Earth, high tides on Earth would be
A) higher. B) lower. C) no different.
Compton Scattering: A certain photon, after being scattered from a free electron that was at rest, moves at an angle of 120° with respect to the incident direction. If the wavelength of the incident photon is 0.591 nm, what is the energy of the scattered photon? (melectron = 9.11 × 10-31 kg, c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s)
A. 1.05 × 1016 J B. 2.10 × 1016 J C. 5.71 × 1016 J D. 3.34 × 1016 J E. 4.21 × 1016 J