Consider the consequences of being handed a helium-filled small balloon tethered to a string, and its eventual outcome and respond to these questions with an explanation that would be clear to other students too.

1. Why does the balloon rise when it is filled?

2. What forces act on the balloon as it rises, and once it reaches the limit of the cord you are holding it by?

4. If your mass were 75 kg, that's roughly 165 lb weight, how would you decide whether to take hold of the balloon? Obviously, if it is large enough, you will be lifted off the ground. You may not know in time to let go if the cord on the balloon were long and horizontal on the ground, so the balloon rose as it moved over you.

5. Suppose you miscalculated and were lifted off the ground, if the cord on the balloon were 10 meters long, how much time elapses while you take a full swing from side to side, calling for help?

6. What fundamental constants of nature determine the behavior we are discussing and its outcome?