The outward pressure in the core of a red giant balances the inward pull of gravity when
A) hydrogen begins fusing into helium.
B) carbon fuses into heavier elements.
C) the electron orbits are compressed so much they are all in contact.
D) the electrons and protons have combined to form neutrons.
E) iron forms in the inner core.
C
You might also like to view...
A nuclear reactor fuel rod is a circular cylinder 6 cm in diameter. The rod is to be tested by cooling it with a flow of sodium at 205°C and a velocity of 5 cm/s perpendicular to its axis. If the rod surface is not to exceed 300°C, estimate the maximum allowable power dissipation in the rod.
GIVEN
• Cylinder in a cross flow of liquid sodium
• Cylinder diameter (D) = 6 cm = 0.06 m
• Sodium temperature (T?) = 205°C
• Sodium velocity (U?) = 5 cm/s = 0.05 m/s
• Maximum rod surface temperature (Ts) = 300°C FIND
• The maximum allowable power dissipation Gq
ASSUMPTIONS
• Steady state
• Turbulence in the sodium flow approaching the rod is low
• Heat generation per unit volume in the rod is uniform
SKETCH
How do we know that a hot main sequence star (and not some other kind of star) is embedded in a cloud of interstellar gas?
What will be an ideal response?
The intensity level of a "Super-Silent" power lawn mower at a distance of 1.0 m is 100 dB. You wake up one morning to find that four of your neighbors are all mowing their lawns using identical "Super-Silent" mowers
When they are each 20 m from your open bedroom window, what is the intensity level of the sound in your bedroom? You can neglect any absorption, reflection, or interference of the sound. The lowest detectable intensity is 1.0 × 10-12 W/m2. A) 80 dB B) 104 dB C) 400 dB D) 50 dB E) 40 dB
If an optical system consists only of an object and a single convex mirror,
a. the image will sometimes be inverted. b. the magnification will sometimes have an absolute value greater than 1. c. the image distance will never be negative. d. the image will always be virtual.