velocity

[fredrick]

A car driven by Jess leaves an intersection and travels due north at 20ms-1 at the same time that a car driven by Kelleaves the intersection due east at 15ms-1.
Calculate the velocity of Kel revative to Jess.

I can get the magnitude of velocity, but the direction?


G00D LUCK TOMMOROW!

[Lugo]

I got a relative velocity of 25ms^-1 at an angle of 306.87^o T

I hope some-one can verify my answer as these relative velocity questions kill me.

[cara.mel]

I got - direction: S (arctan(15/20))º E

but it's been ages since I did these
is it just v_(b relative to a) = v_b - v_a
therefore imagine jess is stationary and Kel is moving at 20m/s south and 15m/s east away from her?
bleh. xD

[Ken]

i get 217ºT from tan^-1 [15/20] = 37º and then +180 =217ºT

[fredrick]

i get 143.1ºT. tan-1(15/20)= 37º, then 180-37=143ºT

L0L

[Mao]

how are you guys measuring true bearing?

N xx W?

I thought it was clockwise, i.e. 143 degrees.

[cara.mel]

yeah 143 would be right if you weren't lazy like me

[Lugo]

Yes I am mistaken,
143^oT is correct