A refrigerator has a coefficient of performance equal to 4.2. How much work must be done on the operating gas in the refrigerator in order to remove 250 J of heat from the interior compartment?
A) 60 J
B) 120 J
C) 250 J
D) 480 J
E) 1050 J
A
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Solenoid: An ideal solenoid of length 10 cm consists of a wire wrapped tightly around a wooden core. The magnetic field strength is 4.0 T inside the solenoid. If the solenoid is stretched to 25 cm by applying a force to it, what does the magnetic field become?
A. 1.6 T B. 10.0 T C. 20 T D. 4.0 T
An inventor tries to sell you his new engine which takes in 40. Joules of heat at 87°C on each cycle, expels 30. Joules at 27°C, and does 10. Joules of work. Why are you not fooled, and can have him prosecuted as a fraud?
What will be an ideal response?
The units of impulse are equivalent to:
a. those of energy. c. kg•m/s. b. N•s. d. those of force.
When a switch is closed, completing an LR series circuit, the time needed for the current to reach one half its maximum value is ____ time constants.
A. 0.250 B. 0.500 C. 0.693 D. 1.00 E. 1.44