If the actual frictional force is equal to 1 lb., then how much effort (force) would be required to drag a 90 lb. box up the plane? a. 10+ lb. b. 10- lb. c.9+ lb. d. 9- lb. could you also explain this? i am having a hard time understanding.

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.

increase masses, decrease separation