- #1

Saalz

- 5

- 1

- Homework Statement
- Vehicle acceleration from wheel torque

- Relevant Equations
- Ftan = Torque / r

F = m * a

I was modeling the dynamics of a vehicle for a project, and started doubting about the way of applying physics in this particular case.

The thing is, I know the torque in the wheels from the torque the electric motor I designed do provide, multiplied by the gearbox ratio. I also know the radius of the wheels, and so, the tangential force in the surface of the tyre.

I'm under the case the wheels do not slip and therefore, the velocity at the circumference of the wheel its the same as the velocity of the car.

Thus, I do apply F = m * a, and isolate acceleration in that equation to calculate it as the ratio between the friction force on the road equal to the tangential force in the wheels, and the mass of the vehicle.

My question following that is, do wheel number matter? As the force is calculated from a single wheel, do I have to multiply it by the number of wheels the vehicle has as each one generates it's own friction force in the road (and, not even of the same magnitude sometimes, as in turns, the differential makes each wheel rotate at different speeds)?

Also, the mass used in the equation is the total mass of the vehicle and each wheel holds a percentage of the total mass of the vehicle. Does that even matter if I use the force in a single wheel?

Or I'm just overthinking and it's as simple and physically correct as using the friction force generated by one wheel and the total mass of the vehicle to know the linear acceleration it has? In that case, why?

Thanks for the replies.

The thing is, I know the torque in the wheels from the torque the electric motor I designed do provide, multiplied by the gearbox ratio. I also know the radius of the wheels, and so, the tangential force in the surface of the tyre.

I'm under the case the wheels do not slip and therefore, the velocity at the circumference of the wheel its the same as the velocity of the car.

Thus, I do apply F = m * a, and isolate acceleration in that equation to calculate it as the ratio between the friction force on the road equal to the tangential force in the wheels, and the mass of the vehicle.

My question following that is, do wheel number matter? As the force is calculated from a single wheel, do I have to multiply it by the number of wheels the vehicle has as each one generates it's own friction force in the road (and, not even of the same magnitude sometimes, as in turns, the differential makes each wheel rotate at different speeds)?

Also, the mass used in the equation is the total mass of the vehicle and each wheel holds a percentage of the total mass of the vehicle. Does that even matter if I use the force in a single wheel?

Or I'm just overthinking and it's as simple and physically correct as using the friction force generated by one wheel and the total mass of the vehicle to know the linear acceleration it has? In that case, why?

Thanks for the replies.