A giant star radiates energy at the rate of 3.0 × 1030 W, and its surface temperature has been measured to be 3000 K. Assuming that it is a perfect emitter, what is the radius of this star? (? = 5.67 × 10-8 W/m2 ? K4)
A) 7.8 × 1010 m
B) 8.7 × 1010 m
C) 1.4 × 1010 m
D) 1.9 × 1011 m
E) 2.3 × 1011 m
E
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A proton is located at the point (x = 1.0 nm, y = 0.0 nm) and an electron is located at the point Find the magnitude of the electrostatic force that each one exerts on the other. (k = 1/4??0 = 9.0 × 109 N ? m2/C2, e = 1.6 × 10-19 C)
A) 1.4 × 10-11 N B) 5.3 × 10-18 N C) 5.3 × 108 N D) 5.9 × 10-15 N
In the most general form of the first law of diffusion, the gradient of the Gibbs free energy with respect to the position of B-type atoms is equal to the chemical _____________on the B-type atoms.
Fill in the blank(s) with the appropriate word(s).
If the intensity of radiation from the sun is 
at a distance of 
at what distance is the intensity 
A. 
B. 
C. 
D. 
E. less than 
km
Constant Acceleration Kinematics: A bicyclist starts a timed race at 6.0 mi/h. In order to win, he must average 21 mi/h. Assuming constant acceleration from the start, how fast must he be traveling at the end of the race?
A. 36 mi/h B. 30 mi/h C. 24 mi/h D. 42 mi/h