Question

7 sandy is standing on the side of the road and observes two cars both moving in the positive direction. sandy measures that car a is moving at 29 meters per second and car b is moving at 21.5 meters per second. to an observer inside car a, how fast is car b moving? 21.5 m/s 50.5 m/s -50.5 m/s -7.5 m/s

Explanation:

Step1: Determine the relative - velocity formula

The relative velocity formula for two objects moving in the same direction is \(v_{BA}=v_B - v_A\), where \(v_{BA}\) is the velocity of car B with respect to car A, \(v_B\) is the velocity of car B with respect to the ground, and \(v_A\) is the velocity of car A with respect to the ground.

Step2: Substitute the given values

We are given that \(v_A = 29\ m/s\) and \(v_B=21.5\ m/s\).
Substitute these values into the formula: \(v_{BA}=21.5 - 29\).

Step3: Calculate the result

\(v_{BA}=21.5−29=- 7.5\ m/s\)

Answer:

\(-7.5\ m/s\) (the fourth option)