# Forces In physics, **force** is defined as *a push or pull that one object exerts on another object*. A push or a pull has both magnitude and direction associated with it, and thus can be represented as a [[Vector Quantities|vector quantity]]. The SI unit of force is called the **newton (N)**. 1 Newton is the force needed to accelerate an object with a mass of $1$ kg at a rate of 1 m/s$^2$. > [!info] **Free-Body Diagrams** > The easiest way to visualize the forces acting on an object is through the construction of a **free-body diagram**, a type of drawing which includes only *the external forces acting on the body of interest*. > > ![[Forces.png|525]] ## Common Forces ### Normal Force > [!example]- **Molecular Interactions of Normal Forces** > ![[Pasted image 20250220173358.png]] ### Tension A tension is a force along the length of a medium ### Friction KInetic friction is a constant value, but static friction is a range of potential values. ### Spring Force ## Net Force The motion of an object is determined by the net external force on the object. ![[Pasted image 20250204233603.png|375]] $F=|\vec{F}|=\sqrt{F_x^2 + F_y^2}$ $\theta = \tan^{-1}(\frac{F_y}{F_x})$ $F_x=F\cos(\theta)$ $F_y=F \sin(\theta)$ ## Relationship Between Force & Acceleration ![[Force.png|400]] The same force is being exerted on both the car and the basketball, but different accelerations are being produced ## Free-Body Diagrams > [!info] Drawing Free-Body Diagrams > > >