advertisement

PHY 2020 Homework Set #2 Fall 2014 Name: Due: At the start of class on Friday, Sep 5, 2014. (Not 5 minutes after the start of class.) If you just give an answer without showing how you arrived at that answer, then you will get no credit for the problem. 1. Bob and Alice are going to race each other. But Alice believes that she is faster than Bob so she will run 100 m to the finish line, and Bob starts 20 m ahead of Alice. They begin the race at the same time, and they cross the finish line at exactly the same time. Alice crossed the finish line after running for 12 s. (a) How long did it take Bob to cross the finish line? (b) What was Alice’s speed during the race? (c) What was Bob’s speed during the race? 2. Now they do something a bit different. Alice and Bob start 100m apart and are now going to race towards each other. Assume that they are running with the same speeds as in the first problem. (a) How far will Alice run before she meets Bob? (b) How far will Bob run before he meets Alice? (c) How much time will Bob and Alice be running until they collide? 1