(forces and motion) in 2-3 sentences explain why velocity (or speed) is interesting

Which is not a source of noise pollution? a)airplanes b)acid rain c)machines d)cars

In what direction does the medium move relative to the direction of the wave? explain.

Acoil formed by wrapping 80 turns of wire in the shape of a square is positioned in a magnetic field so that the normal to the plane of the coil makes an angle of 28.0° with the direction of the field. when the magnetic field is increased uniformly from 200 µt to 600 µt in 0.400 as, an emf of magnitude 80.0 mv is induced in the coil. what is the total length of the wire?