Take a spring, stretch it an inch or two, and imagine the force exerted by it. You will have no difficulty with this problem, and a layman or child will have no difficulty either, especially if you use the term “pull” instead of “force” in your question. Now take a second similar spring, hook it to the first one, and stretch the combination until each spring is extended to the same distance as the single spring before. When you then ask about the pull, most nonphysicists will state that it is obviously twice what it was before, because there are two springs instead of one. Try to convince them that the force has the same magnitude as before, because each spring is stretched by the same amount! How would you proceed?