# I Torque to Overcome Static Friction of a Rolling Object

1. Dec 4, 2017

### ALincoln21

I am doing some calculations to optimize the power to weight ratio and gearing of a RWD car. I have torque charts and can calculate the force put to the track by each wheel and the static frictional force by the track on each wheel. I am trying to determine what the minimum speed is for the car to be moving before the car is no longer able to spin its tires (overcome static friction), and repeat this process for each gear. Any ideas on how to approach this problem??

2. Dec 4, 2017

### CWatters

I think it's quite straight forward..

The max torque that can be delivered to the wheels without slipping is the max Frictional force * wheel radius. If the car can deliver more torque than that the wheels can spin (I mean slip).

You should be able to plot two lines on the same graph of torque vs velocity...

1) A horizontal line for the max torque that friction can handle.
2) A curve for the available torque vs velocity.

The point where 2) dips below 1) will be the velocity you are looking for.