F=ma for rigid bodies proof

The video tutorial explains how the formula F=MA, typically applied to particles, can be extended to rigid bodies. It begins by reviewing the basic concept of F=MA for particles and then introduces the challenge of applying it to rigid bodies with multiple forces acting at different points. The tutorial simplifies the problem by considering a rigid body made up of three particles and uses free body diagrams to illustrate internal and external forces. Through simultaneous equations and Newton's Third Law, the internal forces are shown to cancel out, leading to a proof that the sum of external forces on a rigid body equals the total mass times the acceleration of its center of mass.

What happens to the internal forces when summing all forces acting on a rigid body?

How is the center of mass defined in relation to the particles of a rigid body?

Describe the process of deriving the equation for the motion of a rigid body from the forces acting on its particles.

What is the final conclusion regarding the sum of external forces acting on a rigid body?