Why do manual cars/motorcycles stall if you don’t give them gas as you let go of the clutch?
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#ELI5
The car is at idle. You’re not giving it any gas.
The engine’s output is low, because you’re not giving it gas.
The engine has to keep the air conditioner working, and power steering, power brakes, and generate electricity for the lights, radio … *the engine has WORK to do*.
And it’s able to do only so much work while idling.
Now you let out the clutch, and you’re asking the engine to move the car too! You’re asking it to do more work than before!
But at idle, it doesn’t have any more “oomph”. It’s using up all the work it can produce, to run fan belts, power steering, air conditioner. It can’t move the car forward too!
So you have to give it more gas, which makes it rev higher, which makes it able to do more WORK.
………… Follow-on …………
Take any car (manual or not), and sit in it, with car in park, at idle. Give it no gas. Make sure your air conditioner is OFF.
Listen to the sound of the engine. Maybe there’s a tachometer so you can see the RPMs.
Be very quiet …..
Now turn on the AC.
You might notice that the car is now revving just a teensy bit higher. The RPMs may be going a teensy bit higher.
That’s because the car said “Oh my, Fun-Juice wants to run the air conditioner now too?? I better rev higher all by myself, so that I can do more work.”
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