Two wires, each having a weight per unit length of 1.0 × 10^?4 N/m, are strung parallel, one 0.10 m above the other. If the wires carry the same current, though in opposite directions, how great must the current in each wire be for the magnetic field of the lower conductor to balance the weight of the upper conductor?
7.1 A
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Emission is called fluorescence if the decay time is less than _________ seconds.
Fill in the blank(s) with the appropriate word(s).
As you are standing on the lakeshore on a calm day, a friend in a boat 300 m offshore calls out to you. Simultaneously, a friend who is 300 m inland yells to get your attention. Which one will you hear first?
A. the friend offshore B. the friend inland C. you will hear both at the same time D. sound can't carry that far
The pressure inside a commercial airliner is maintained at 1.00 atm (105 Pa). What is the net outward force exerted on a 1.0 m × 2.0 m cabin door if the outside pressure is 0.30 atm?
a. 140 N b. 1 400 N c. 14 000 N d. 140 000 N
A baseball outfielder throws a baseball of mass 0.36 kg at a speed of 34.0 m/s and initial angle of 30°. What is the kinetic energy of the baseball at the highest point of the trajectory? Ignore air friction
a. zero b. 312 J c. 156 J d. 52.0 J e. 208 J