# I got a question about relative velocities

velocity of B relative to A is -10 m/s or 10 m/s

i am very confusing this. if i change the question to velocity of A relative to B , IS the answer same as above?~

Doc Al
Mentor
If the velocity of B relative to A is +10 m/s along some axis, then the velocity of A relative to B will be -10 m/s.

Yes, as Doc has said. Both A and B can consider their own velocity to be zero. They both consider the other to be the one going 10 m/s. There is no law of physics that allows you to make an absolute distinction between who is moving and who is not.

If the velocity of B relative to A is +10 m/s along some axis, then the velocity of A relative to B will be -10 m/s.
what do you mean by along some axis

Yes, as Doc has said. Both A and B can consider their own velocity to be zero. They both consider the other to be the one going 10 m/s. There is no law of physics that allows you to make an absolute distinction between who is moving and who is not.

Thank you i got it

Doc Al
Mentor
what do you mean by along some axis
A velocity such as -10 m/s only makes sense with respect to some direction.