A long wire is known to have a radius greater than 4.0 mm and to carry a current uniformly distributed over its cross section. If the magnitude of the magnetic field is 0.285 mT at a point 4.0 mm from the axis of the wire and 0.200 mT at a point 10 mm from the axis, what is the radius of the wire?
a. 4.6 mm
b. 7.1 mm
c. 5.3 mm
d. 12 mm
e. 10 mm
c
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A molecule takes 3.0 seconds to diffuse across a membrane. If the thickness of the membrane is doubled, then how long does it take the molecule to diffuse across the thicker membrane?
A. 30 hours B. 24 hours C. 20 hours D. 18 hours E. 12 hours
A child is riding a merry-go-round that is turning at 7.18 rpm. If the child is standing 4.65 m from the center of the merry-go-round, how fast is the child moving?
A) 5.64 m/s B) 3.50 m/s C) 0.556 m/s D) 1.75 m/s E) 1.80 m/s
Jennifer hits a stationary 200. gram ball and it leaves the racket at 40. m/s
If time lapse photography shows that the ball was in contact with the racket for 40. ms: (a) What average force was exerted on the racket? (b) What is the ratio of this force to the weight of the ball?
Which of the following has not yet been proved practical?
a. Fusion reactor b. Fusion bomb c. Fission bomb d. Fission reactor