# Cyclist

• Dec 29th 2008, 10:09 PM
magentarita
Cyclist
Cyclist A is travelling at 22km/h in the direction N 35 E and a second cyclist is travelling at 17 km/h in the direction S 40 E. Determine the relative velocity of A with respect to B.
• Dec 30th 2008, 03:00 AM
HallsofIvy
Quote:

Originally Posted by magentarita
Cyclist A is travelling at 22km/h in the direction N 35 E and a second cyclist is travelling at 17 km/h in the direction S 40 E. Determine the relative velocity of A with respect to B.

B, himself, "with respect to B" is standing still. To change from "traveling at 17 km/h in the direction S 40" E to "0" velocity, you need to subtract the velocity vector. Do the same to A: subtract the vector "17 km/h at S 40 E" from "22 km/h at N 35 E".

You can do that either by setting it up as a triangle and using the cosine and sine laws or by separating the vectors into components. Would you like to try that yourself?
• Dec 30th 2008, 08:57 PM
magentarita
ok...
Quote:

Originally Posted by HallsofIvy
B, himself, "with respect to B" is standing still. To change from "traveling at 17 km/h in the direction S 40" E to "0" velocity, you need to subtract the velocity vector. Do the same to A: subtract the vector "17 km/h at S 40 E" from "22 km/h at N 35 E".

You can do that either by setting it up as a triangle and using the cosine and sine laws or by separating the vectors into components. Would you like to try that yourself?

I am reviewing some of the lessons taught last semester in preparation for calculus 1. However, our teacher did not cover much about vectors and so this area of algebra is unclear to me and most of the studens who took precalculus in the fall 2008.