What are the outward forces that act on a star? What are the inward forces? How do these compare?
What will be an ideal response?
Answer: The outward forces on a star are radiation pressure caused by nuclear fusion in the stellar cores. This tends to blow up the star. The inward forces are due to gravitation, which tend to compress the star. How do these opposite forces compare? They're equal, and determine the size of the star. When one becomes stronger than the other, the size of the star changes.
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Thermal radiation is defined as
A) radiation with a spectrum whose shape depends only on the temperature of the emitting object. B) radiation produced by an extremely hot object. C) radiation that is felt as heat. D) radiation in the form of emission lines from an object.
State the two laws of thermal radiation
What will be an ideal response?
During this century, we have found that Newton's physics does not apply to
A) high speed objects. B) very strong gravitational forces. C) very small objects. D) All of the above. E) Nonsense--Newton's physics always applies.
An ac series circuit consists of a voltage source, an 880-? resistor, and an inductance L. (There is no capacitance in the circuit.)
The current amplitude is 0.60 A, and the phase angle between the source voltage and the current has a magnitude of 41°. (a) Does the source voltage lag or lead the current? (b) What is the voltage amplitude of the source?