Answer:90 m/s
Explanation:
Given
Speed of both the car is [tex]v=45\ m/s[/tex]
Suppose North side and East side as Positive Y and x axis
so Velocity of car A can be written as
[tex]v_a=45\hat{i}[/tex]
Velocity of car B is
[tex]v_b=-45\hat{i}[/tex]
Velocity of car A relative to car B is given by
[tex]v_{ab}=v_a-v_b[/tex]
[tex]v_{ab}=45\hat{i}-(-45\hat{i})[/tex]
[tex]v_{ab}=90\hat{i}[/tex]
Magnitude of velocity is
[tex]|v_{ab}|=90\ m/s[/tex]