7. If there are two straight lines with different slopes in the distance and time graph, do you think the speeds of the motions are the same or different? If they are different, how are they different and why do you think so?

answer(20) psi;

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.

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.