How to calculate starting torque and working torque of a drilling machine?

Question

If I knw the power and the rpm (indicated on the plate), do I make use of the equation: Power = Torque * rpm? Will I be calculating, starting torque or working torque, with this equation?

Next which among the following drilling machine is the most powerful?

1.Power = 500 W and rpm = 500

2.Power = 500 W and rpm = 1000

3.power = 750 W and rpm = 2000

4.power = 750W and rpm = 3000

Answer 1

"If I knw the power and the rpm (indicated on the plate), do I make use of the equation: Power = Torque * rpm?"

Actually, if you want your torque in N·m, you will want to use the equation Power=Torque * rad/s. Using the equation Power=torque*rpm will give you a result that is too large by a factor of 30/π. (since 1 rpm = π/30 rad/s). Still, since this factor is constant, it won't matter if all you're doing is making a simple comparison - clearly, in any units, machine #1 is the most powerful.

The torque that you will be calculating is the working torque. Generally, the starting torque will be higher for an electric drill.