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• When you turn a car’s steering wheel, the car follows a path along the same curve regardless

• whether you go forwards or backwards. So it seems like it should be just as easy to steer

• going backwards as going forwards. But clearly, it's not.

• Suprisingly, the difficulty of driving backwards has almost nothing to do with the direction

• youre facing and everything to do with the fact that you steer using the front wheels.

• When driving forwards, a car goes in the direction the front wheels are pointed. And when driving

• backwards, the car goes where the back wheels are pointed. Simple! But the difference is

• that going forwards, the direction of travel is determined by the same wheels you steer

• with, so you just point them where you want to go, and that’s where you go, the back

• wheels follow automatically. In physics, we call this a “stablesystem, like dangling

• a pencil from your fingersmove your hand around and the pencil follows, no thought

• required.

• However, when driving backwards, the direction of travel is determined by the back wheels

• but you steer with the front wheels. So rather than just pointing the front wheels where

• you want to go, you have to point them in the direction that will get the BACK wheels

• to point in the direction you want to goit’s an additional level of separation before the

• car does what you want. And in fact, if you don’t make any corrections, then over time

• the back wheels point farther and farther away from the direction you want to go: instead

• of following the front wheels, they want to run away!

• This is an unstable system, like trying to balance a pencil on your fingertip. It’s

• incredibly finicky and requires a ton of coordinated hand-eye feedback to maintain. That’s why

• your car is like an upside-down pencil!

• Of course, there are some successful rear-steering wheeled vehiclesforklifts, for example,

• drive only slowly and choose rear-steering for greater control of their forks.

• But let’s go in the other direction and add a TRAILER to your carsteering backwards

• has gained ANOTHER level of difficulty: you use your front wheels to get the back wheels

• to point in the direction needed to get the TRAILER to point in the direction you want

• to go. Not complicated enough? It becomes worse the more trailers you addeach one

• adds another level of separation between the direction of your steering and the actual

• direction of travel. Which is why it’s nearly impossible to push on one end of a chain or

• a rope and have the other end go where you want it to, and why you will never, ever balance

• a flexible rope or chain upright on your finger. Makes backwards driving seem downright easy!

When you turn a car’s steering wheel, the car follows a path along the same curve regardless

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B1 US direction steering driving steer pencil front

# Why is it Harder to Drive Backwards?

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Ashley Chen posted on 2015/03/02
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