# directional forces

by DaveC426913
Tags: directional, forces
 P: 15,325 Are "direction of force" and "plane of application" valid concepts in mechanical physics, or are these terms I've made up? Just from the terms alone I'd assume that plane of application is perpendicular to direction of force. But I wonder if that's always the case.
 Sci Advisor HW Helper Thanks PF Gold P: 26,109 Hi Dave! "direction of force" is certainly essential in mechanical physics - Newton's second law (which is about as fundamental as you can get!) says applied force = (rate of change of) momentum, and momentum certainly has a direction. The direction is as much an essential part of any force as it is of any velocity, or of any momentum or acceleration! In mathematical terms, force is a vector (and so, like velocity, momentum, or acceleration, obeys the vector "law of addition"). "plane of application" …? … I haven't come across.
P: 4,780
 Quote by DaveC426913 Are "direction of force" and "plane of application" valid concepts in mechanical physics, or are these terms I've made up? Just from the terms alone I'd assume that plane of application is perpendicular to direction of force. But I wonder if that's always the case.
Sounds about right to me. You can use whatever definition you want as long as you state what you mean by it.

P: 15,325

## directional forces

Well, this is going in to a school science book, so I want to ensure I use legitimate concepts.
 P: 4,780 If you want to be super picky about it, forces have a magnitude and a direction. They are distributed on a differential area normally and tangentially. As the differential area collapses the differential force acts on a point. A plane of application would imply a stress, not a force.

 Related Discussions Calculus & Beyond Homework 8 Calculus & Beyond Homework 4 Introductory Physics Homework 1 Introductory Physics Homework 3 General Math 2