In order to keep an object weighing 40 Newtons moving at constant speed along a horizontal surface, a force of 15 Newtons is required. The force of friction between the surface and the object is

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?