Relation between torque and speed

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    Relation Speed Torque
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SUMMARY

The relationship between torque and speed in DC motors and crankshafts is characterized by an inverse proportionality, as established by power calculations. Torque is defined as the twisting moment required for rotation; without it, rotation ceases. In electrical motors, a constant power output occurs within a specific speed range, where torque decreases as speed increases. Conversely, fuel-consuming engines exhibit a convex torque curve, peaking near maximum RPM, indicating that the inverse relationship is not universally applicable.

PREREQUISITES
  • Understanding of DC motor mechanics
  • Familiarity with power calculation formulas
  • Knowledge of torque and RPM relationships
  • Basic principles of engine performance curves
NEXT STEPS
  • Research the torque-speed characteristics of different types of DC motors
  • Study the power calculation formula in detail
  • Examine torque curves for various internal combustion engines
  • Learn about the implications of torque and speed in mechanical design
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Engineers, mechanical designers, and students studying motor dynamics and engine performance will benefit from this discussion.

PhysicsBegner
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Hi Everyone, It is said that speed is inversly propotional to torque ( in Dc motors or a crank shaft powered by engine). I understand that torque is a twisting moment that makes the shaft to rotate, if no torque is applaid then shaft won't rotate. With this context; it is hard for me to understand how we say torque is inversly propotional to speed logically, although a simple math (from power calculation formula) would say they are inversly propotional.
Could anyone help me in this?
 
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In some electrical motors, there's is a range of rotational speed where power output is nearly constant, where torque decreases as rotational speed increases. This is generally not the case with (fuel consuming) engines. Generally the torque curve versus rpm is a convex curve, with a peak usually near the upper range of it's maximum rotational speed, and power increases as rotational speed increases until very near maximum rotational speed.
 
So is it not valid to we make a generic statement that speed is inversly propotional to torque? And does it only applies to certain cases?
 

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