Final answer:
Drivers should give a bicyclist at least 1 meter of space when passing. In the bicyclist's reference frame, a stationary observer on a sidewalk would appear to move in the opposite direction of the bicyclist's travel. A pedestrian needs to ensure there is ample space between them and a car traveling at the speed limit to safely cross, which generally translates to several car lengths.
Step-by-step explanation:
To answer how much space you are required to give a bicyclist as you pass, laws can vary by location, but a common rule is to provide at least 3 feet or about 1 meter of space between your car and the bicyclist. This helps ensure the safety of the cyclist and is required by law in many places.
Regarding the reference frame of a bicyclist, if you are standing on a sidewalk and a cyclist passes by to your right, in the cyclist's reference frame you would appear to be moving to the left. This is a result of the relative motion concept, where the motion is observed relative to the other object's frame of reference.
For the question about crossing the road, if a car is traveling at 60 km/h (which equals 16.67 meters per second) and a car length is 3.5 meters, the car will travel certain distance while you walk 2 meters. Since we need to cross 4 meters in total (2 meters further than the width of the car), you would need to ensure there is enough distance for the car to cover this space without reaching you.
It is important to wait until the car is several car lengths away for safety, however, the objective distance cannot be determined without knowing the pedestrian's walking speed.