I want to model a car movement. The equations are: [tex]\sum[/tex]F = ma [tex]\sum[/tex]T = m [tex]\alpha[/tex] The forces are, weight of the car, normal force and f the friccional force, but also the engine provides a constant rotational acceleration in my model. I understand that the frictional force is the one that moves the car, so: f = ma But also the movement of the engine generates Torque, and I can't realize how to connect this with the torque of the friccional force. Because if the car engine stop the frictional force stop the wheel but when the car engine is connected to the wheel they must oppose. It's correct to say something like: Torque (of car engine) - Tf (of frictional force) = I[tex]\alpha[/tex] ¿Does the frictional forces opposes to the rotation of the wheel car in the rotational movement?? I can't complete the movement description.