Final answer:
In the reference frame of the bicyclist moving to the right, a stationary observer on the sidewalk would appear to be moving to the left due to the principles of relative motion.
Step-by-step explanation:
When monitoring the path of your rear wheels during a left turn, you should use your left outside mirror. This mirror provides the best view of where your rear wheels are in relation to the curb and other vehicles. For the physics-related question involving a bicyclist and an observer standing on the sidewalk, we must consider relative motion. The observer on the sidewalk, when viewed from the bicyclist's reference frame, would appear to be moving to the left. This is because relative motion dictates that if you are moving towards the right in relation to the ground, stationary objects will seem to be moving to the left. It's similar to what you experience when sitting in a moving train and seeing the landscape glide by in the opposite direction of your travel.