What is Torque?
Torque, also called moment of force, is the rotational equivalent of force. It measures the tendency of a force to rotate an object about an axis. The formula is ? = r x F x sin(?), where ? is torque, r is the lever arm distance, F is force, and ? is the angle between force and lever arm. Torque is measured in newton-meters (N?m) or pound-feet (lb?ft). Maximum torque occurs when force is perpendicular to the lever arm (? = 90 degrees).
Torque in Everyday Life
You experience torque whenever you turn something. Opening a door, tightening a bolt with a wrench, or pedaling a bicycle involves torque. The longer the wrench handle (lever arm), the more torque you generate with the same force. This is why it's easier to open a door by pushing far from the hinges. Car engines are rated by torque because it determines acceleration ability. Higher torque means better ability to overcome resistance and accelerate heavy loads.
Applications of Torque
Torque is critical in mechanical engineering. Automotive engineers design engines to produce optimal torque curves for performance. Machinists tighten bolts to specific torque values to prevent over-tightening or under-tightening. Robotics engineers calculate torque requirements for robot joints. Torque wrenches ensure precise fastening in aircraft, cars, and machinery. Understanding torque explains why gears work (trading speed for torque or vice versa), why longer wrenches are more effective, and how electric motors compare to combustion engines.
Quick Tips
- Always verify units are consistent
- Use scientific notation for very large/small numbers
- Results are approximations — real conditions may vary
Frequently Asked Questions
Force causes linear acceleration, while torque causes rotational acceleration. Force is measured in newtons, torque in newton-meters. Torque depends on both force magnitude and distance from the rotation axis.
Torque is rotational force, while horsepower is power (work per time). They're related: HP = (Torque x RPM) / 5252. High torque at low RPM gives good acceleration; horsepower determines top speed.
A longer wrench increases the lever arm distance (r), so the same force produces more torque (? = r x F). This demonstrates mechanical advantage through leverage.
Yes, torque direction depends on rotation direction. By convention, counterclockwise torque is positive, clockwise is negative. Net torque determines angular acceleration direction.
A torque wrench allows precise control of applied torque, crucial for fasteners that require specific tightness. Over-tightening can strip threads or break bolts; under-tightening causes loosening.