Suppose you are riding a bike with a speed of `20 m//s` due east relative to a person A who is walking on the ground towards east. If your friend `B` walking on the ground due west measures your speed as `30 m//s`, find the relative velocity between two reference frames `A and B`.

Options

A. Velocity of `A` w.r.t `B` is `5 m//s` towards east
B. Velocity of `A` w.r.t `B` is `5 m//s` towards west
C. Velocity of `A` w.r.t `B` is `10 m//s` towards east
D. Velocity of `A` w.r.t `B` is `10 m//s` towards west

Answer

C

Explanation

`vec v_(AB) = vec v_(A, you) + vec v_(you, B) = -vec v_(you, A) + vec v_(you,B)`
=`(-20) + 30 = 10 m//s` east.