# How do I calculate the best mass for the highest linear speed?

I have a motor whose specifications say that its torque is 190g*cm. If I have the formula for the mass of the wheel vs radius, is there any way I can find the radius to get the best linear speed?

The formula that relates mass and radius is

$m=1.14r-0.948$

where the m is mass in grams and r is radius in cm

• Minimizing your wheel diameter will maximize your linear speed. Your comment from link italic bold code this page concerns me about the motor getting hot. Are you sure you're using a 12V, 400 mA power supply for the motor. Too many amps can fry the motor. It sounds like your constraint for max launch speed of the ping pong ball is a wheel large enough to launch the ball. – morristtu Nov 4 '15 at 0:50
• You cannot determine a speed from the parameters that you have given. At the very least, you will need to know the motor speed (rpm) for various torques. – hazzey Nov 4 '15 at 2:16
• That is why I am changing the mass of the wheel - to try to make the motor work for setup. The only data point I have is 15200 rpm at 190g*cm. See link – electricviolin Nov 4 '15 at 3:22