The modern physics learns that one body is influenced by several forces. These forces can be caused by natural influence or external. Many tasks come down to search of one of such forces, but stay demands knowledge of net force. Net force is the sum of every effort made for a body. She submits to Newton's laws. Let's sort how to find net force.
Instruction
1. For a start it is necessary to understand that net force depends on a condition of a body. If bodies is in rest, then it is affected by two forces. weights pulls force body down. Also being on any surface, the body is affected by force of reaction of a support which is directed vertically down. When finding net force of F = Ft+ (-N)=0. Force of reaction of a support is directed opposite to gravity therefore it undertakes with a minus sign. Therefore, the body which is in rest has net force equal to zero.
2. Let's analyze situation when the body is influenced by the third-party force which forces to start moving a body. The vector is forces in the first case is directed perpendicular to gravity. Then the body is affected by four forces. Gravity, force of reaction of a support, friction force and force of draft which forces a body to move. Knowing that force of reaction of a support is equal to mg, and is opposite to gravity, their equally effective is equal to zero. Therefore, equally effective it is equal to the difference of friction forces and draft.
3. In case the body forces to move force which is at an angle to force of reaction of a support. It is necessary to enter counting from abscissa axis which will be directed towards the movement. Friction force undertakes with minus whereas force of draft is calculated according to trigonometry. Vectors of force of reaction of a support and force of draft, form a triangle between which corner undertakes on a cosine as the party of a vector of reaction of a support adjoins to a corner, and a draft force vector, is a hypotenuse. Therefore, force of reaction of a support will be expressed by a formula cosA*F. Knowing that force of reaction of the mg support, will find force of draft and equally effective which is directed as draft force.