A ball is dropped from a height of 1.20 m and hits the floor. The ball compresses and then reforms to spring upwards from the floor to a height of 0.86 m. The time from the ball's first contact to when it left contact with the floor was 0.091 s. Calculate the ball's acceleration while it is in contact with the floor.

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.)