When you stretch a spring 13 cm past its natural length, it exerts a force of 21 n. what is the spring constant of this spring?

Explanation:

From Hooke's law,

Substistuting the values, you can ignore the minus sign, since it is there to state that the force is always in the opposite direction of the deformation, and has no influence otherwise, and your constant is

50 inches should be the resultant vector

c) up is the direction the magnetic force is acting on the charge.