Which of these example would illustrate that work in being done? A) an airplane sits on the runway ready to takeoff B) a weightlifter attempts to pick up the barbell, but it does not move C) a construction worker pushes on a concrete wall until he becomes exhausted D a high school freshman lifts a backpack full of textbooks onto her shoulder

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.)