Forces and Free Body Force Diagrams – GCSE Physics A (Combined) OCR Revision

Forces are pushes or pulls on an object that can cause an object to accelerate, decelerate, or change its direction.
The resultant force is the sum of all the forces acting on an object.
If the resultant force on an object is zero, this means it is either stationary or moving with constant speed.
If the resultant force is not zero, the object will either accelerate or decelerate.
Free body force diagrams (also known as force diagrams) are graphical illustrations used to visualize the forces acting upon an object.
In a free body force diagram, the object is usually represented by a dot (the free body) and the forces as arrows pointing in the direction of the force.
The larger the force, the longer the arrow representing it.
Each arrow in the diagram represents a different acting force like gravity, friction, tension, and applied forces.

To draw a free body force diagram, first identify all the forces acting on the object.
Draw each force as an arrow starting from the center of the object, pointing in the direction the force is acting.
Label each arrow with the type of force it represents.
If there are multiple forces acting in the same direction, they should be added together to find the resultant force.
When forces are acting in opposite directions, subtract the smaller force from the larger force to find the resultant force.
An object at rest or moving at a constant velocity has a net force of zero; this is due to all the forces acting on the object being balanced.

Understanding forces and free body force diagrams is crucial for predicting how objects will behave when subjected to multiple forces.
These diagrams provide a clear way to visualise and calculate the resultant force acting on an object.
Understanding forces and how to represent them in diagrams is fundamental to many areas in physics, from understanding earth’s gravity to the principles of flight and beyond.