During which of the following phases of life is a star's balance of pressure and gravity out of equilibrium?
A) when it is on the main sequence
B) when it is undergoing helium core fusion
C) when it is a white dwarf
D) when it is expanding as a red giant
E) A star is never out of equilibrium.
D) when it is expanding as a red giant
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Power: A series circuit contains a 20-? resistor, a 200-mH inductor, a 10-?F capacitor, and an ac power source. At what frequency should the power source drive the circuit in order to have maximum power transferred from the driving source?
A. 0.45 kHz B. 0.17 kHz C. 0.28 kHz D. 0.96 kHz E. 0.11 kHz
How high a hill would a 75-kg hiker have to climb to increase her gravitational potential energy by 10,000 J?
What will be an ideal response?
The magnitude of the magnetic field that a long and extremely thin current-carrying wire produces at a distance of 3.0 µm from the center of the wire is 2.0 × 10-3 T. How much current is flowing through the wire? (?0 = 4? × 10-7 T ? m/A)
A) 380 mA B) 190 mA C) 30 mA D) 19 mA
The rotational inertia of a pencil is greatest about an axis
A) along its length, where the lead is. B) about its midpoint, like a propeller. C) about its end, like a pendulum.