Posting here hoping for a physics-based reply. Not 1 with so many physics equations. I've just disliked opinions that've probably contradicted reality.
I viewed a vid re power versus torque in vehicles. My understanding is that power is torque multiplied by angular velocity. Given an amount of power, a high-torque vehicle doesn't have a very high top velocity. A high-velocity vehicle won't tow a very massive load.
I related it to my little knowledge re stick shift. Gear 1 is used to move a stopped vehicle or for low speeds. Does gear 1 mean max torque and lowest angular velocity? I think you need a high torque to overcome static friction. Does gear 2 mean a dip in torque and a rise in angular velocity? Does the max gear mean lowest torque and max angular velocity? When I was young, a driver said one can carefully switch from gear 1 ➡️ 2 then 2 ➡️ 3 then 3 ➡️ 4 (and so on) on a wide road with very few surrounding vehicles. He said it'd up the velocity and a high gear generally meant more fuel-efficient.
Please correct me if any of the above is wrong.
I googled. Here's what I read –
"Revolutions per minute" is how many revolutions the engine itself is making per minute. The gear ratios then translate revolutions of the engine into revolutions of your tires (more or less). Lower gear means lower tire revolutions per engine revolution, but also the tires are easier to turn.
So when the car is going slower, meaning it requires more force to accelerate, you want lower gears. As the car speeds up, you need less force to go faster or maintain that speed, so you switch to a higher gear, sacrificing power for more efficient use of your engine.
I didn't ask an llm to avoid hallucinations.
Yes, that's correct. You should also remember the difference between (linear) velocity and acceleration. When you say "high torque vehicle won't go very fast" it's true if by fast you mean high velocity. However it will accelerate very quickly, and if the torque exceeds static friction you will get wheel spin.
In fact, there are cases when you want to intentionally lower the torque. For example, in snow it might be difficult to start moving in first gear, but way easier in second.
Another factor is that engines have different power output at different RPM. So at the same linear velocity, lower gears will increase torque both by reducing the angular velocity, and by increasing the output power of the engine itself.
And finally, yes, higher gears usually mean better fuel efficiency. Internal combustion engines have an optimum number of RPMs, and higher gears let you drive at high (linear) speeds while the engine is closer to the optimum RPM number.
So if you want to get somewhere faster you would "drive out" the gears, i.e. only change when almost hitting the RPM limit of the engine. This gives you the best torque. If you want to save fuel, you would "short shift", i.e. change to higher gears as fast as possible while you accelerate.