A 750.0 N man, carrying a 1.9 kg physics textbook, stands at the center of a frozen pond of radius 9.0 m. He is unable to get to the other side because of a lack of friction between his shoes and the ice. To overcome his difficulty, he throws his textbook horizontally at a speed of 7.0 m/s toward the north shore. How long (in s) does it take him to reach the south shore?

Answer 1

Use conservation of momentum to obtain his velocity V after throwing the book.

750 V - 1.9*7.0 = 0

V = 0.01773 m/s

Then divide 9.0 m by that velocity to obtain the time required. It will be over 8 minutes

The assumption of zero friction is probably unrealistic in this case, but that is what they expect you to do.