## What is the lever arm?

He **lever arm **is the perpendicular distance from the axis of rotation to the line of action of force. The magnitude established for the study of this process is τ = N m. The lever arm is related to the torque present at a particular point.

The distance established by the lever arm works as a force amplification factor, as can be seen in levers in general.

This relationship ultimately creates a torque and can be graphed by extending a line of action of force along with a perpendicular line coming from the point of rotation to create a right angle.

**What is a lever?**

A lever is defined as a machine whose function is to transfer force and displacement in order to increase the mechanical force, speed or distance traveled by a rigid bar.

To express the movement carried out by a lever, in physics elements such as force (represented with an “F”), power (represented with a “P”) and resistance (represented with an “R”) are taken.

There are three types of lever: first degree, second degree and third degree levers.

**first grade lever **

The first degree lever is the one where the fulcrum (or fulcrum) is between resistance and power. The latter can be less than the resistance. A clear example of this type of lever would be scissors, a rocker or pliers.

**second degree lever **

The second degree lever is the one where the resistance can be located between the fulcrum and the power. In this case, the latter will always be less than the resistance.

A clear example of this type of lever would be the oars of a boat, a nutcracker and even a wagon.

**third degree lever **

The third degree lever is the one where the power can be found between the fulcrum and the resistance. A characteristic of this type of lever is that the applied force is much greater than the resulting force.

An example of this type of lever would be a fishing rod, staple removers and even the temporomandibular joint of a person or animal.

**How to calculate the lever arm?**

The lever arm appears frequently when wanting to perform a torque calculation. In order to carry out this procedure, it is first necessary to determine the lever arm and then multiply it by the applied force.

As we said previously, the lever arm is the perpendicular distance present between the axis of rotation and the line of action of force.

The initial equation would be:

Torque on a wrench = Force X Lever arm.

The equation to determine the lever arm is:

Lever arm = r SenѲ.

From then on it is only necessary to clear the lever arm in order to determine its magnitude.

You can also calculate the lever arm in a slightly more general situation and not so much a physical problem.

For this, it is necessary to observe the force applied to the body or object and from there consider the existence of a line perpendicular to the force that is being applied and that is crossing the point of interest that we want to determine.

## Lever Arm Examples

A seesaw. Scissors. catapults. Pliers. Nutcracker.

**References**

Lever Arm. Retrieved from merriam-webster.com.

Torque and Equilibrium. Retrieved from hyperphysics.phy-astr.gsu.edu.