physics
posted by Matt on .
a man drives with an average speed of 25 mph for 20 minutes. he rests at his destination for 1 hour and then returns home with an average speed for this leg of the trip of 15 mph
A) what is his average speed for the round trip
B) What is his average velocity for the round trip

distance one way = 25mi/hr * 1/3 hr = 25/3 mi
total distance = 50/3 mi
total time = 1/3 +1 + (25/3)/15 = 17/9 hr
avg speed = 50/3 mi / 17/9 hr = 150/17 = 8.82 mi/hr
avg velocity = 0, since he traveled no net distance.