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Car and Cornering on Flat Roads


For any object to curve, or turn in part of a circle, its inertia must be changed. This is done by applying a force. This force is called a centripetal force and it can be supplied by may sources -friction, gravity, etc.

Car enthusiasts refer to this centripetal force as a "lateral force." The greater the lateral force the greater the speed a car can travel around a curve. Car magazines such as, "Car and Driver," report this lateral force as a lateral acceleration in g's. To use it with standard physics equations it must be converted to m/s2.

Lateral g's are calculated by driving car clockwise and then counterclockwise around a dry circular test track. The car speeds up while maintaining its path along the circular track. When the car skids out of control its velocity is noted and the centripetal acceleration is calculated.

Most street cars can provide a lateral g of 0.6 to 0.90. That is a wide range. A lateral acceleration of "1g" means that the car is producing a sideways acceleration equal to its weight. There are some sports car that produce more than 1g laterally. That's an exercise you can do with an Internet search.

 

 
Example

A 2016 Mazda 3 has a lateral acceleration of 0.81 g's. (a) How fast can this car "take" a city street corner with a radius of 20.0 m without sliding?

Solution

 

 

 
 

by Tony Wayne ...(If you are a teacher, please feel free to use these resources in your teaching.)