In a manual car, why does going switching down gears make it easier/possible to to uphills?
In: Engineering
It’s exactly the same process that happens with a pushbike.
If you move into a lower gear, for the same speed your legs move, you now move more slowly.
You can put a given amount of force in to turn the crank once.
If you need more power to get up hills, you put the bike in a lower gear, so that means now to move forward one meter, for example, you have to turn the crank 3 times.
If you’re in top gear on a pushbike, you might only turn the crank 1/8 of a turn to move forward a meter.
So considering you put out a certain amount of force to turn the crank once, in low gear, you’ve now got three times that force to move 1 meter. The gears allow you to exchange speed for torque, or pulling power.
In top gear, once the bike is moving fast, you don’t need anything like as much power to maintain that speed, so you can move into the top gear, spreading your body’s force out along more distance.
The car’s engine works the same way. If you move down the gears, a given number of revolutions of the engine now are responsible for moving the car less distance, so the car has that much more power to move.
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