Vectors
- In physics, during force interactions, it is common to represent situations as simply as possible without losing information
- When considering force interactions objects can be represented as point particles
- These point particles should be placed at the center of mass of the object
- Force vectors that act upon that objects should be drawn with their tail on that point particle
- The length of the force vector corresponds to its strength
- The longer the vector, the greater the force magnitude
- The below example shows the forces acting on an object when pushed to the right over a rough surface
Point particle representation of the forces acting on a moving object
- The below example shows an object sitting on a slope in equilibrium
Three forces on an object in equilibrium form a closed vector triangle
- The below example shows the forces acting on an object suspended from a stationary rope
Free-body diagram of an object suspended from a stationary rope
Examiner Tip
When labeling force vectors, it is important to use conventional and appropriate naming or symbols such as:
- w or Weight force or mg
- N or R for normal reaction force (depending on your local context either of these could be acceptable)
Using unexpected notation can lead to losing marks so try to be consistent with expected conventions.