Jack's Physics Adventure on Frictionless Ice Pond!

How can Jack get back to shore on the frictionless pond?

A. Use his heavy physics textbook
B. Swim across the pond
C. Wait for someone to rescue him

Answer:

A. Use his heavy physics textbook

Jack can exploit the conservation of momentum by tossing his physics textbook in the opposite direction to which he wishes to move. The momentum gained will propel him towards the shore. The force used in the throw, according to Newton's Second Law, will determine the rate of his movement, with greater force minimizing the time taken to reach the shore.

Explanation:

The situation in this question involves the principle of conservation of momentum and Newton's Second Law. The conservation of momentum is a fundamental concept in physics that states that if no external forces are acting upon a system, the total momentum remains constant. In this scenario, since the frictionless ice provides no external force, Jack's system (which includes himself and his backpack) should have a constant momentum. Jack can throw the heavy physics textbook in the direction opposite to the one he wishes to move. By doing this, the textbook acquires some momentum in one direction and, to conserve the total momentum of the system that was initially zero, Jack gains equal momentum in the opposite direction. Regarding part b), according to Newton's Second Law (Force equals mass times acceleration, F=ma), the more force Jack uses to throw the book, the higher his acceleration will be, thus minimizing the time it takes to reach the shore.