When an electric current flows through a long conductor, each free electron moves
a. back and forth between the ends of the conductor.
b. from one end of the conductor to the other end.
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c. with a speed of 300,000,000 m/s.
d. through a relatively short distance.

According to social exchange theory, altruistic behaviors benefit the individual who performs them.

The ability to make things happen is also called a. heat b. force c. matter d. energy

Estimate the kinetic energy of mars with respect to the sun as the sum of two terms, that due to its daily rotation about its axis, and that due to its yearly revolution about the sun. (assume mars is a uniform sphere with mass = 6.4×10 to the power of 23 kg, radius = 3.4×10 to the power of 6 m, rotation period = 24.7 hours, orbital period = 686 days and is 2.3×10 to the power of 8 km from the sun.)