A box with a mass of 15.0 kg is being pushed on a level surface with a horizontally applied force. It just starts to slide when 40.0 N is applied
and will continue to slide if 35.0 Nis applied to the box. What is the
coefficient of static friction (us) of these surfaces? *

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?

How do we measure or think of speed in the united states?

Amoving electron has kinetic energy k1. after a net amount of work w has been done on it, the electron is moving one-quarter as fast in the opposite direction. (a) find w in terms of k1. (b) does your answer depend on the final direction of the electron's motion?