1. A man is stranded in the middle of an ice rink that is perfectly frictionless. How can he get to the edge?

2. A girl jumps from a boat to a dock. Why does she have to jump more energy than she would need if she were jumping the same distance one dock to another?

3. Much early search in rocket motion was done by Robert Goddard, physics professor at Clark College in Worcester, Massachusetts. A quotation from a 1921 editorial in the New York Times illustrates the public acceptance of his work: "That Professor Goddard with his 'chair' at Clark College and the countenance of the Smithsonian Institution does not know the relation between action and reaction, and the need to have something better than a vacuum against which to react---to say that would be absurd. Of course, he only seems to lack the knowledge ladled out daily in high schools." The belief that a rocket needs something to push against was a prevalent misconception before rockets in space were commonplace. Explain why that belief is wrong.