a block of mass m is pulled along a horizontal frictionless surface by a rope of mass m .if a force f is applied at the free end of the rope, the net force exerted on the block will be

it is very well related to a lot of things but with my limited knowledge i can confidently say that the answer is space.

i will answer your question if you answer mine

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.