Moving Reference Frames: One Car Passing Another

[Kristenx2]

Homework Statement

You are traveling in a car going at a constant speed of 100 km/hr down a long, straight highway. You pass another car going in the same direction which is traveling at a constant speed of 80 km/hr. As measured from your car’s reference frame this other car is traveling at -20 km/hr. What is the acceleration of your car as measured from the other car’s reference frame? What is the acceleration of the other car as measured from your car’s reference frame? Give an explanation to your answers.

Homework Equations

The only equation I personally have in my notes is a_t=a_w or w_t=w_wt+w_w. Note that I have no idea what these equations mean, I just scribbled them down as my professor flicked through the slides.

The Attempt at a Solution

I figured that my vehicle would be accelerating at 20 km/hr², and the other car would be accelerating at -20 km/hr². Is this correct? I am not sure if I am doing anything right.

 

[HallsofIvy]

Is that really the question? You are told that both cars are moving constant speed. While speed is "relative", acceleration is not! The acceleration of both cars is 0 in any reference frame.