The Greek astronomer who assigned the stars to six magnitudes was named _______________
a. Aristotle
b. Socrates
c. Hipparchus
d. Panos
c
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Ohm's Law: A light bulb operating at 110 V draws 1.40 A of current. What is its resistance?
A. 12.7 ? B. 78.6 ? C. 109 ? D. 154 ?
According to Wein's Law, if the surface temperature is increased by a factor of 2, its peak wavelength will:
A) increase by a factor of 2. B) decrease by a factor of 2. C) increase by a factor of 4. D) decrease by a factor of 4. E) not change; Wein's law has nothing to do with peak wavelength.
Most galaxies we see are moving away from us. How do we know this?
a) Light we receive from each galaxy has a longer wavelength than we expect. b) Each galaxy appears visibly smaller as time passes. c) We can see that the galaxies are getting dimmer from year to year. d) Light we receive from each galaxy has a shorter wavelength than we expect.
A centrifuge takes 100 s to spin up from rest to its final angular speed with constant angular acceleration
. A point located 8.00 cm from the axis of rotation of the centrifuge moves with a speed of 150 m/s when the centrifuge is at full speed. (a) What is the average angular acceleration of the centrifuge as it spins up? (b) How many revolutions does the centrifuge make as it goes from rest to its final angular speed?