Two very short friends, John and Jack, were living together in an apartment.
Since they frequently lost their apartment key, they decided to leave it on top of the door frame whenever they left home.
In order to reach the key, John had to climb on Jack’s shoulders to take it down from the frame.
Yet John was the taller and the heavier guy of the two. Why didn’t Jack climb on his shoulders instead?
The reason is that as being taller, John also had longer arms. If Jack climbed on John’s shoulders, he wouldn’t have reached the key.
