I have 2 related questions, the second one is more engineering than physics, but it relies on the first.
Does it take more force to get a car to start moving than to accelerate it the same amount while it is already moving?
For example, to get it from 0 to 5 mph vs 40 to 45 mph.
I ask this because the gear ratio of car gears is higher for low gears. This does two things, it increases the torque (and wheel force) in lower gears and increases the rpm's of the engine for lower wheel speeds.
Is the only reason high gear ratios are used for lower gears to raise the engine rpm's from the wheel rpm's (because engine speed wants to be around 2-4000), or is it because you need that additional torque to get the car to start moving.