Meaning and mechanism
Torque describes the turning effect of a force about an axis. The perpendicular lever arm is the shortest distance from the rotation axis to the force’s line of action.
Even a small force can produce a large torque with a long lever arm. The same suspended mass has different effects close to and far from the pivot.
Relationships and conditions
When considering forces acting vertically, the value is τ=Fd, while the force of the weight is mg. We verify whether the sum of the opposing torques, with reversed signs, is 0.
The experiment omits measurements of bar mass and friction with axes, etc. If an object does not move as a whole with rotational equilibrium, the forces must also be in balance.
What to observe in the simulation
Different masses balance when mass times lever arm is equal.
The rigid lever is massless and the pivot frictionless. Tilt highlights net torque direction and is not a dynamic solution. Do not reproduce real load tests.
Key relationships and symbols
τ = mgd · Στ = τright − τleft
| Symbol | Meaning | Unit |
|---|---|---|
| τ | Torque | N·m |
| d | Perpendicular lever arm | m |
| F | Applied force | N |
Worked example
What is the balance condition?
Equal opposing torques · Different masses balance when mass times lever arm is equal.
Common misconceptions
- Instead of using any distance from a given point to the focus, you must use the distance perpendicular to the line of action of the force.