10. Mary and John are seated on a bench a distance 2m apart. Suddenly, John moves closer to Mary and claims that he has been drawn by the gravitational force. Is John’s claim justifiable? Show quantitatively. (Assume the masses of John and Mary are 67 kg and 55 kg respectively, and the coefficient of static friction between John and the bench is 0.15

d) physical means can be used to separate the components of air.

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.