"Force perpendicular" is a concept, not a specific value. It refers to the component of a force that acts at a right angle (perpendicular) to a particular surface or direction. To understand what's "equal to" force perpendicular, we need more context.

Here are some possibilities:

* Equal and opposite force perpendicular: Newton's Third Law states that for every action, there is an equal and opposite reaction. If a force is applied perpendicular to a surface, the surface will exert an equal and opposite force perpendicular back.

* Normal force: This is the specific term for the force exerted by a surface perpendicular to an object in contact with it. It's equal in magnitude and opposite in direction to the component of the object's force that is perpendicular to the surface.

* Component of a force: A force can be broken down into components that act in different directions. The component of a force that acts perpendicular to a surface or direction is called the "perpendicular force".

* Torque: When a force acts at a distance from an axis of rotation, it can create torque. The perpendicular component of the force is the one that contributes to the torque.

To give you a more precise answer, please tell me:

* What is the specific situation you're considering?

* What is the surface or direction the force is perpendicular to?

* What else is involved, like a lever, a frictionless surface, or an object's motion?

Once I understand the context, I can help you determine what is equal to the perpendicular force in your specific case.