Quote:
Originally Posted by orange4boy
That part, I know. I know about BSFC and engine efficiency. It's the theoretical part I'm looking for. Forget about engines and cars for a minute. Think physics class. I know, it hurts.
Does it require more energy to create the same amount of kinetic energy? ball 1: 10mph in 10 seconds vs ball 2: 10mph in 5 seconds. Theoretically, I don't think it does. I'm just trying to confirm this so I can fully understand.
Getting back to cars: If all the difference in losses between accelerating faster and slower have to do with engine efficiency then there is no limit on how fast you accelerate for FE but the engine BSFC. I realize there may be other factors like increased friction.
I was under the assumption that the energy required to accelerate to X speed over time was exponential but I now think it's directly proportional. Just cant seem to find a source that can confirm this.
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KE is just related to speed, so in a vacuum/frictionless surface it doesn't matter how long it takes you to get to whatever speed, you'll use the same amount of energy to do it.
For cars in general the limiting factor is engine BSFC and for automatics tcc lockup since torque converters are really inefficient. The energy required to accelerate to some speed, assuming a manual trans or tcc locked most of the way is proportional to the speed squared. Since brakes are just devices that turn KE into heat, braking distance is also proportional to speed squared, eg someone's KE/braking distance at 70mph is about twice that of someone at 50mph.