What would a drummer do to make the sound of the drum give a note of lower pitch?

If steel is more dense that lake water, why can a boat float

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?

What causes the formation of ocean currents?