Violet light (? = 430 nm) is incident on a piece of potassium (? = 2.20 eV). What is the maximum kinetic energy of the ejected photoelectrons? (h = 6.63 × 10^?34 J?s, c = 3.00 × 10^8 m/s, 1 eV = 1.60 × 10^?19 J, and 1 nm = 10?9 m)
a. 2.43 eV
b. 0.69 eV
c. 2.89 eV
d. 5.09 eV
e. 0.96 eV
b
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A brass rod with a length of 20.0 cm is placed side by side with an aluminum rod with a length of 20.0 cm and this system is placed between a hot temperature of 150
and a cold temperature of -10.0
The coefficient of thermal conductivities of the brass and the aluminum are 100 W/m 
and 230 W/m C respectively. The rods have the same cross sectional area of 20.0 cm2. What is the heat flow from the hot temperature to the cold temperature?
A. 683 W B. 528 W C. 52.8 W D. 68.3 W
Which of the following is (are) invariant(s)?
A. mass B. momentum C. energy D. the speed of light E. mass and the speed of light
Bohr's atomic theory predicted energy levels for hydrogen of En = (2 ?2 k2 e4m)/(hn)2. If instead we place 1 electron in "orbit" about a bare nucleus of atomic number Z, how do you expect Z to be incorporated into the En formula and why?
What will be an ideal response?
It is late and Carlos is sliding down a rope from his third-floor window to meet his friend Juan. As he slides down the rope faster and faster, he becomes frightened and grabs harder on the rope, increasing the tension in the rope. As soon as the upward tension in the rope becomes equal to his weight:
a. Carlos will stop. b. Carlos will slow down. c. Carlos will continue down at a constant velocity. d. the rope must break.