As a pelican flies through the air, it flaps its wings, thereby pushing down on the air below. What is the reaction force? A the force of air resistance that resists the pelican's forward movement
B the air pushing back up on the wings of the pelican
C the force of gravity pulling the pelican down
D the air around the pelican pushing down on other air molecules farther below

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.)