Forces and Free Body Diagrams

When dealing with forces we need to take into account all of the various forces acting on an object. To do this we create force body diagrams or little pictorial representations of what is going on. Then we can assign equations to each component and from there solve backwards to our answer choice.

Since these questions can come up in a variety of different scenarios we will walk through several examples step by step . Look out for the similarities between each since the core process for drawing a free body diagram is the same.

Flat Surfaces

We will start by considering our rock from the last article.

Scenario 1: Rock Sitting on the Ground

In this scenario, we will look at a rock sitting on the ground from here on out we will use boxes to represent the object we are talking about regardless of its original shape. Additionally, we will use the same steps each time so you can begin to understand how to go through different force problems in a consistent way.

  1. Draw the scenario
  2. Define the force of gravity
  3. Define any pushing or pulling forces
  4. Define the normal force
  5. Determine what you are solving for
  6. Work backwards to solve

Scenario 2: Pushing the Rock to the Right

Scenario 3: Pushing on the Rock but It Doesn’t Move

Inclined Planes

Scenario 1: Rock on a Plane

Pulleys and Ropes