Whether the universe is open, closed or flat depends on the ____ of the universe
a. luminosity
b. density
c. temperature
d. radius
e. rotation rate
B
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A long hollow cylindrical conductor (inner radius = 2.0 mm, outer radius = 4.0 mm) carries a current of 24 A distributed uniformly across its cross section. A long wire which is coaxial with the cylinder carries an equal current in the opposite direction. What is the magnitude of the magnetic field 3.0 mm from the axis?
A. 0.82 mT B. 0.93 mT C. 0.70 mT D. 0.58 mT E. 0.40 mT
An elevator weighing 20 000 N is supported by a steel cable. What is the tension in the cable when the elevator is being accelerated upward at a rate of 3.00 m/s2? (g = 9.80 m/s2)
a. 6.1E+3 N b. 2.0E+4 N c. 6.0E+4 N d. 2.6E+4 N e. 6.7E+3 N
Why is 2,4,5-trifluorophenol much more acidic than phenol?
A) The fluorines adjacent to the OH group are large and shield the hydroxl group from making the solution basic. B) The fluorines de-stabilize the benzene ring and thus give the structure more acidic characteristics. C) The fluorines have high electronegativities and help to stabilize the negative charges, which makes it even easier for the hydrogen to be lost. D) False! 2,4,5-trifluorophenol is actually not more acidic than phenol.
A concave mirror has an object placed 40 cm in front of it. An image forms 60 cm in front of the mirror. What is the focal length of the mirror?
A. 60 cm B. 120 cm C. -120 cm D. 100 cm E. 24 cm