Your forehead can withstand a force of about 6.0 kn before fracturing, while your cheekbone can only withstand about 1.3 kn. a. if a 140 g baseball strikes your head at 30 m/s and stops in 0.0015 s, what is the magnitude of the ball's acceleration? b. what is the magnitude of the force that stops the baseball? c. what force does the baseball apply to your head? explain. d. are you in danger of a fracture if the ball hits you in the forehead? in the cheek?

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.)