A student jogs around a park two times, starting and ending at the gate to the park. The jogging track is a square, with 40 m on each side. Which of the following statements is
true about the student’s distance and displacement?
a. The distance is 320 m, and displacement is 160m.
b. The distance is 160m, and the displacement is 40 m.
c. The distance is 320m, and the displacement is 320 m.
d. The distance is 320 m, and the displacement is 0

Certain bacteria (such as aquaspirillum magnetotacticum) tend to swim toward the earth’s geographic north pole because they contain tiny particles, called magnetosomes, that are sensitive to a magnetic field. if a transmission line carrying 100 a is laid underwater, at what range of distances would the magnetic field from this line be great enough to interfere with the migration of these bacteria? (assume that a field less than 5% of the earth’s field would have little effect on the bacteria. take the earth’s field to be 5.0 * 10-5 t, and ignore the effects of the seawater.)