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(1) An idealized engine with constant torque curve means constant acceleration.

So for example if there is no air resistance and no frictions and car is on fixed gear and at 3000Rpm it produces 50Hp so at 6000Rpm will produce 100Hp.

So he doubles the speed , doubles power and got constant acceleration.

(2) So if we look at equation Ek = 1/2mv^2 which means if You want to accelerate same as before to twice a speed You need 4 times of energy per second(or horsepower per second) So this is what I don't understand because first example shows that car need twice more power at twice speed to same amount of acceleration.

Car with CVT gearbox which acceleration from 0-100km/h in 10s doesn't need 40s to accelerate from 100-200km/h even when air resistance is much bigger (goes quadratic as well)

(3) Higher speeds require more energy for subsequent speed increases, hence at constant power, acceleration goes down. Why we need more energy when speed is increases? Because gravity want to pull as or what? And why we don't need more energy in space to acceleration at higher speed?

(4) Why it works in cars and doesn't work for example in space? I mean Rocket egine produce same amount of energy per second but acceleration is constant and doesn't decrease when speed increases ?

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