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angry

What makes a car turn?

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I can''t get my head around why a car turns when you turn the steering wheel which rotates the wheels. The contact patch stays on the same location as before(or thats what I think), so what makes the car turn, and not keep driving forward?

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Friction.

Sliding friction (sideways on a wheel) is more than rolling friction (forwards and backwards on a wheel). This means that a car will always try to go in the direction that the wheel is facing.

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Actually it depends on whether the car is front wheel drive or rear wheel drive.

If the car is rear wheel drive, then there is a thrust force acting perpendicular to the rotational axis of the rear wheels, oriented either forward or reverse (depending on the gear box). When the front wheels are turned, the reaction force from the road onto the front tires now acts at an angle relative to the plane of rotation of the front wheels. This imparts a component of force parallel to the plane of rotation and one perpendicular to this plane. This latter force provides the energy to turn the front of the car in the direction that the wheels are pointing.

If the car is front wheel drive, then the thrust force produced by the front wheels has two components; one perpendicular to the front axle(s) and one parallel to it. This latter force provides the energy to turn the vehicle. The former component also partly explains why front wheel drive vehicles without power assisted steering tend to understeer in corners.

Hope this helps a little.

Cheers,

Timkin

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