What observations demonstrate the existence of an interstellar medium?
What will be an ideal response?
1) We can see the three different types of nebulae with the aid of optical telescopes. 2) As starlight travels through the ISM, gas atoms can absorb specific wavelengths and form interstellar absorption lines in the spectra of those stars. Astronomers can distinguish interstellar absorption lines from stellar absorption lines in a number of ways. 3) You expect from Kirchhoff's second law (Chapter 7) that an excited low-density gas viewed against an empty or colder background should produce an emission spectrum, and the ISM does exactly that.
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You throw a ball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down
A) Work up is -, and the work down is -. B) Work up is +, and the work down is +. C) Work up is -, and the work down is +. D) Work up is +, and the work down is -.
The intensity of a sunspot is found to be 3 times smaller than the intensity emitted by the solar surface. What is the approximate temperature of this sunspot if the temperature of the solar surface is 5800 K?
a. 4400 K b. 470,000 K c. 1900 K d. 7600 K e. 1400 K
A rifle bullet shot horizontally has a vertical acceleration of ______________
Fill in the blank(s) with correct word
A ball of mass mB is released from rest and acquires velocity of magnitude vB before hitting the ground. The ratio of the magnitude of the momentum the Earth acquires to the magnitude of the momentum the ball acquires is
A.
B.
.C.
.D.
E.
.