posted by T mann on .
A train at a constant 41.0 km/h moves east for 38 min, then in a direction 44.0° east of due north for 25.0 min, and then west for 59.0 min. What are the (a) magnitude (in km/h) and (b) angle (relative to north, with east of north positive and west of north negative) of its average velocity during this trip?
First travel segment is 41*38/60 = 25.97 km east.
Second travel segment is 41*25/60 = 17.08 km, 44 degrees east of north.
That has components of 17.08 sin44 = 11.87 km east and 17.08 cos44 = 12.29 kn north.
The third displacement is 40.32 km weast (-40.32 km west).
Add up the total resultant diplacements north and east. Divide them by 38 + 25 + 59 = 122 minutes = 2.067 hours to get average (resultant) velocity components in km/h.
The angle east of north is arctan Rx/Ry, where Rx and Ry are the resultant displacements east and north.
What exactly is the angle. I got 100.55 degrees and it says it is wrong