A heat pump is used to heat a house in Minnesota in the winter and has half the ideal coefficient of performance for a reversible heat pump. If the outside air temperature is 
and the indoor temperature desired is 
what is its coefficient of performance under these conditions?
A. 3.7
B. 1.1
C. 2.0
D. 4.2
D. 4.2
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The attraction of the Moon causes tides on Earth. Because of friction, tidal action slows the rotation of Earth. What happens to the angular momentum of the Earth-Moon system, and does this affect the motion of the moon?
What will be an ideal response?
A fan blade, initially at rest, rotates with a constant acceleration of 0.025 rad/s2 . What is its angular speed at the instant it goes through an angular displacement of 10 rad?
a. 0.025 rad/s c. 0.46 rad/s b. 0.11 rad/s d. 0.71 rad/s
Energy and Mass: One of the first atomic bombs released energy equivalent to that of 20,000 tons of TNT explosive. How much mass was converted to energy by this explosion, given that 1000 tons of TNT produce 4.3 × 1012 J of energy. Incidentally, modern H-bombs have energy yields 1000 times as much! (c = 3.0 × 108 m/s)
Fill in the blank(s) with the appropriate word(s).
If j = 90° – q, what is the value of sin2 j + sin2 q?
a. 0 c. -1 b. 1 d. The answer depends on q.