John and Henry push a piano with 800N, and the piano refuses to move. According to the definition of work in physics, there is NO work done on the piano.

With i really need the correct answer!

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?

Which two particles are found in the center of an atom