Relation between speed and torque
Speed is inversely proportional to torque IF YOU HOLD POWER FIXED. But that is usually not the way it works, that you hold power fixed.
Let me re-arrange that equation and break it down for you using standard units. When you are thinking of the mechanical power at the shaft of the motor, this is how it works:
P = torque * speed
Where P is power in Watts. Torque is in Newton-meters. Speed is shaft speed in radians per second.
So, if you speed up and keep the torque constant, that takes more power. If you increase the torque and hold the speed constant (like going up a hill in a car) that takes more power. That makes sense, right?
This is analogous to the physics of a mass moving against a force in a straight line.
P = force * speed
Where P is power in Watts, force is in Newton-meters, and speed is in meters per second.
Note: 1 revolution per second = 2 * pi radians per second.