If the mass of the book is 50 sliding with acceleration 1.2 m/s ^ 2 then the friction force is

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.

measure their densities same density, same sub

does anyone know or what?

that would be because of both gravity and friction. so     c