<span>So what happens when there is more than one force? I like to think of net force as if two people were pulling on ropes attached to a big crate. If they pull the crate in the same direction, the crate will accelerate twice as quickly. If they pull in opposite directions with equal forces, the crate won’t move at all — these two forces cancel each other out. If one person pulls northwards and the other pulls eastwards, the crate will move to the north-east.
The number of neutrons is variable, resulting in isotopes, which are different forms of the same atom that vary only in the number of neutrons they possess. Together, the number of protons and the number of neutrons determine an element's mass number.
