# Gear ratio requirement (RPM --> km/h)

1. Feb 6, 2015

### D.B0004

1. The problem statement, all variables and given/known data
A vehicle having wheels with a diameter of 58cm, is powered by motors that have a maximum speed of 6024 rpm. Each motor is coupled to the wheel using a gear mechanism as shown in figure 2-14. Calculate the required gear ratio if the vehicle's maximum speed is 190.2 km/hr.

Note: Answer is a unitless value, correct upto two decimals.

2. Relevant equations
No clue. C = 2 * PI * R?

3. The attempt at a solution
I converted 6024 rpm to radians per second hoping I could do the same with hm/hr, but I do not know the radius of the tire? See photo attache for diagram. Thanks for help.

File size:
13.9 KB
Views:
151
File size:
22.3 KB
Views:
281
2. Feb 6, 2015

### Quantum Defect

... but you know the diameter of the wheel. How is diameter related to radius?...

3. Feb 6, 2015

### CWatters

I would start "at the other end of the problem". eg Work out the rpm of the wheel at max velocity.