The Rock in a Boat in a Pool problem

Post your answer and explanation as a comment below.

This problem is famous for stumping Robert Oppenheimer, one of the most famous physicists of the 20th Century and two of his physicist pals George Gamow and Felix Bloch so don't be afraid to try! You can demonstrate and prove the answer with some plastic containers and a rock! Oppenheimer directed the Manhattan Project which led to the development of the first atomic bomb. After seeing the first ever explosion of an atomic bomb in the New Mexico desert, he said ‘we knew the world would not be the same’. He later opposed the development of an even more powerful hydrogen bomb.