How is Average Velocity Calculated for a Two-Part Journey?

[kx250f341]

A car travels east at 73 km/h for 1.4 h. It then travels 30.0° east of north at 129 km/h for 0.5 h.
(a) What is the average speed for the trip?
87.7 km/h

(b) What is the average velocity for the trip?
Magnitude ____ km/h
Direction ____

Homework Equations

V avg= delta r/delta t
delta r= rf-ri/tf-ti

The Attempt at a Solution

64.5km-102.2km=-37.8km
.5h-1.4h=-.9h

(-37.8km)/(-.9h)=42.1 km/h

not sure how to find the direction, but I am doing my h.w. online and it tells me my answer is incorrect. Am I even going in the right direction?
Any help please?

 

[PhanthomJay]

Average velocity is total displacement divided by total time. You have to get the total displacement by vectorially adding up the 2 displacement vectors.

 

[kx250f341]

so Jay you are saying I have to find the x and y comp to find the total displacement

 

[PhanthomJay]

Yes, get the x and y components of each of the 2 displacements you have calculated, add up each separately, then get the resultant displacement magnitude and direction using pythagorus and trig. That's the total displacement, you have the time, solve for the average velocity magnitude and direction.