a 5kg mass is hung from the end of a coil spring . If the system is made to vibrate without SHM of period 2sec, find the energy of the motion if the amplitude of vibration is 3cm

this could be newton#'s law of cooling. the cooling curve is exponential

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.