PLEASE HELP ANSWER THIS QUESTION ! 1) Joel has tied a 0.25 kg stone to the end of a 0.85 m rope. As he spins the rock above his head, Joel exerts a 45.5 N centripetal force to keep the stone in circular motion. Based on this information, what is the period, T, of the stone's circular motion.

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.

you get 2.3=1.21*\frac{a}2 or 4.6=1.21a or a=3.802 (b)

explanation: