What is torque?
By: Tessa Nicholson & Derk Clothier
Torque is the force that causes an object to rotate around its axis (usually called the pivot) and acquire angular acceleration.
The symbol for torque is τ, the Greek letter tau.
There are three factors that affect torque:
- the amount of force applied
- the direction of the force
- the angle between the applied force and the radius.
Everyone has a basic understanding of torque from pushing open a door. The door handle is on the opposite side of the hinges because it takes considerably less force to open a door there than it would if the handle was closer to the hinge. The greater the force you apply, the faster the door will open. Finally, force has to be applied perpendicular to the access in order for there to be torque.
Static vs. Dynamic:
Static torque can be a force applied that produces no movement.
Or, static torque can refer to an object spinning at a constant rate with no acceleration.
Dynamic torque is a force applied that causes angular acceleration.
In general torque is the rate of change of angular movement, but specifically Torque can be measured by using the formula:
- T = f (perpendicular force) x distance to the pivot
How is torque different from a simple force?
Force is the effort to change a stationary object to moving or vice versa in a linear motion. When force is used to move an object on a pivot in a twisting motion, the force is then called torque.
This demonstration shows that the angle between the force and the radius affect the amount of torque produced.
This demonstration shows static torque in motion.
Having an understanding of torque is beneficial for knowing the best way to distribute weight and angles to produce the largest rotational movement with the least amount of effort. This knowledge can help you open doors easier, move items, and fix the wheels on your car!
There are many science curriculum outcomes and indicators that a lesson on torque could be used in. For example:
- In grade two for Motion and Relative Position 2.1, students need to analyze methods of determining the position of objects relative to other objects.
- In grade five one of the physical science, forces and simple machines outcomes is 5.2, which is to investigate characteristics of simple machines, including levers, wheels and axles, pulleys, inclined planes, screws, and wedges, for moving and lifting loads. Torque is essential for investigating simple machines and students would benefit from this understanding.
Physics Demos. (2016, August 31). Torque Demo: Tee. [video file]. Retrieved from
Physics Demos. (2016, September 8. Torque Demo: Wheel. [video file]. Retrieved from
Saskatchewan Ministry of Education. (n.d.). Saskatchewan Curriculum: Education: The future within us. Retrieved from
(2018). Torque. In Torque and Angular Movement. Retrieved from
(2018). What is Torque?. Retrieved from University of Guelph, Department of Physics: