At a carnival, you can try to ring a bell by striking a target with a 8.91-kg hammer. in response, a 0.411-kg metal piece is sent upward toward the bell, which is 3.88 m above. suppose that 21.9 percent of the hammer's kinetic energy is used to do the work of sending the metal piece upward. how fast must the hammer be moving when it strikes the target so that the bell just barely rings?

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.)