Torque

Torque, in physics and engineering, is the rotational equivalent of linear force. It is a measure of the force that can cause an object to rotate about an axis. More specifically, torque is the tendency of a force to twist or rotate an object around an axis, fulcrum, or pivot. It depends on the magnitude of the force applied, the distance from the axis to the point of force application (the lever arm), and the angle between the force vector and the lever arm. The greater the force or the longer the lever arm, the greater the torque. torque is a vector quantity, possessing both magnitude and direction, with its direction defined by the right-hand rule. Its unit of measurement is typically the Newton-meter (N·m) in the SI system or pound-foot (lb-ft) in the imperial system.

Torque meaning with examples

• When tightening a bolt with a wrench, the applied force at the end of the wrench creates torque. The longer the wrench, the greater the lever arm, and the less force needed to achieve a specific torque value, ensuring a secure fastening. Mechanics use torque wrenches calibrated in Newton-meters or pound-feet to ensure proper tightness, preventing damage from overtightening or loosening. This precise application is vital for many car parts, like cylinder head bolts, to prevent engine malfunctions and to guarantee structural integrity of automotive parts.
• The engine's crankshaft generates torque which causes the car wheels to turn. This engine torque is transmitted through the transmission and axles. Higher torque values, especially at lower engine speeds (RPM), translate to quicker acceleration and improved ability to climb hills, regardless of the vehicle weight or its body shape. The amount of engine torque can vary considerably by the engine type, size, and forced induction systems like turbochargers and superchargers can substantially increase torque output.
• Aerodynamic forces acting on a helicopter's rotor blades produce lift, but they also generate a counter-torque, causing the helicopter's body to rotate in the opposite direction. Tail rotors are designed to counteract this torque. By controlling the thrust generated by the tail rotor, the pilot maintains the desired heading and prevents uncontrolled spinning of the helicopter's body. If the tail rotor fails, the aircraft will spin uncontrollably, causing a crash because of this imbalance.
• A cyclist's legs apply torque to the pedals of a bicycle, causing the chain and wheels to rotate. The efficiency of pedaling, the effective effort, depends on the applied force, the length of the crank arms (lever arm), and the cadence (pedaling speed). Cyclists can shift gears to adjust the mechanical advantage, changing the relationship between pedaling effort and wheel rotation, allowing them to adapt to varying terrain and maintain a desired pedaling cadence. This is also known as angular momentum.