A guitar string with a linear density of 0.0020 kg/m is stretched between supports that are 0.58 m apart. The string is observed to form a standing wave with three antinodes when driven at a frequency of 424 Hz.
(a) What is the frequency of the fundamental mode of vibration of this string?
(b) what is the speed of the wave on the string?

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.)