A reflection nebula is caused by:
A) starlight reflected off of a surface.
B) sunlight reflected off of a surface.
C) sunlight scattered by dust particles.
D) starlight scattered by dust particles.
E) emission by ionized gas.
D
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The diagram above shows the life track of a 1 MSun protostar from the time it first begins to form until it reaches the main sequence, with four stages labeled. What is happening to the protostar's surface temperature and luminosity during Stage 3, when it is undergoing radiative contraction and its life track moves up and to the left?
A) Its surface temperature and luminosity increase. B) Its surface temperature remains the same and its luminosity decreases. C) Its surface temperature and luminosity decrease. D) Its surface temperature decreases and its luminosity increases. E) Its surface temperature and luminosity remain the same.
Graphical Analysis: The graph in the figure shows the position of a particle as it travels along the x-axis. 
At what value of t is the speed of the particle equal to 0 m/s?
A. 0 s B. 1 s C. 2 s D. 3 s E. 4 s
Lenz's Law: As shown in the figure, two parallel wires carry a current I in opposite directions, and this current is decreasing. A rectangular loop is centered between the wires. The direction of the induced current through the resistor R is
A. from a to b. B. from b to a. C. No current is induced.
Assume 3.0 moles of a diatomic gas has an internal kinetic energy of 10 kJ. Determine the temperature of the gas after it has reached equilibrium
a. 270 K b. 160 K c. 800 K d. 1 550 K e. 400 K