how come if you jump in a train you will land in the same spot but if you jump on top of the train you won't? i tried to make it make sense.

Well, it has to do something with the force of the train. It's pulling you, a force of gravity

However jumping off results in a different sort of energy, the train know is moving farther away as you jump down. So you end up in a different place

Explanation:

b

explanation:

bc its just b

two charges are fixed in place on the x-axis as shown. the charge at x = 0 is negative and has magnitude q = 2 μcoulombs (1 μcoulomb = 10-6 coulombs). the charge at x = d, (d = +12 cm), is positive and has magnitude q = 4 μcoulombs. find a point x = xo along the x-axis at which the electric field is zero.