Question

1. a commuting student rushing to get home before her kids get home from school has left campus and is 200m beyond the college gate at exactly 2 : 19 : 20 p.m. The bus stop is 1100m beyond the gate in the same direction. The last bus that will get her home in time departs promptly at 2 : 23 : 00 p.m. She runs the remaining distance at a constant speed of 3.9 m/s.

a.) determine by calculation whether she is running fast enough to catch her bus.

b.) suppose that the 3.9 m/s had been an average speed rather than a constant speed. Would that have any effect on your answer to (a)? explain.

Answer 1

Total displacement to the bus stop from campus is

1100-200=900 meters, since they are in same direction.

Speed of running=3.9 m/s

Time taken to cover this distance=900÷3.9 = 239.7692 seconds

Available time here is 2hrs 23mts-2hrs 19 mts 20 secs

equals 3mintes 40 seconds

That is 220 seconds, which is less than time taken to cover distance.

Hence she cant get Last bus.

b). In this particular case she is running the distance in straight line in single speed the average velocity didn't make any difference.