30 min = .5 h
10 min = 1/6 h
20 min = 1/3 h
=================
d = 140*.5 + 90/6 + 90/3
(it went 90 for a total of 1/2hour???? typo I bet)
average speed = d /total time
the way you wrote it the total time is one hour, but I doubt it.
A car travels a straight road at 140 km/h for 30 min then at 90 km/h for 10 min. It then reverses and goes at 90 km/h for 20 min.
a) Find the average velocity for the entire trip.
b) Find the average speed for the entire trip.
3 answers
The three legs of the trip are
70 km , 15 km , and 30 km for a total time of 1 hour
average velocity = (70 + 15 - 30)/1 = 55 km/h
average speed = (70+15+30)/1 = 115 km/h
velocity involves both magnitude and direction.
Since the direction was reversed for the last part, I used -30
70 km , 15 km , and 30 km for a total time of 1 hour
average velocity = (70 + 15 - 30)/1 = 55 km/h
average speed = (70+15+30)/1 = 115 km/h
velocity involves both magnitude and direction.
Since the direction was reversed for the last part, I used -30
I did not see the reversal of direction