Calculate Torque for Acceleration: 4-Wheel Car with 1000kg Mass & 12m/s Velocity

[michael7777]

I wasnt sure where to post my question. Here goes:

I have a car with 4 wheels and one motor.
The motor drives an axle connected to the back wheels.
The total mass of the car is 1000kg
Each wheel weighs 20kg and is a solid cylinder
The effective frictional force is 0.2
The radius of the wheel is 0.5m
The radius of the axle is 0.05m


If I would like to accelerate at 12m/s from rest:
What is the required torque on each wheel?
What is the required motor torque?

Here is my lame solution which I think is pretty incorrect:
F = ma * m/g + um
Fwheel = (ma * m/g + um) / 4
Twheel =( (ma * m/g + um) / 4 ) * radius
Twheel = ( (1000*12 * 1000/9.8 + 0.2*1000) / 4 ) * 0.5
Twheel = 153086.2 Nm
Tmotor = 4*Twheel = 612344.9 Nm

I think maybe you need Io = (MR^2) / 2
But i don't know

 

[michael7777]

I found a really good website which went a long way in answering my question:

http://www.lastufka.net/lab/cars/why/pit.htm