I have been trying to build an electric go kart, and power requirements (as always) have been the problem. I have been going through some formulas to find out how big of a motor I would need from how much torque is required.
- Weight of vehicle (driver included): 200kg
- Top speed: 20m/s (45mph) acc. (a)= 2m/s^2(10 sec to reach top speed) radius(r)=0.2 (variable tho, this is the problem)
From calculations, F=200kg*2m/s^2=400N, torque=400N*0.2m=80 Nm. If a smaller radius is used(say 0.1 m instead of 0.2 m), less torque is needed(400N*0.1=40Nm). Clearly, there is some misunderstanding, or we would all use smaller wheels if they resulted in less torque needed. What am I doing wrong? maybe I did not understand the formulas correctly? If I am correct, how would you explain using bigger wheel sizes?