Force on a particle between two charged plates.

Electrostatic force upon a particle within a uniform electric field.

For this Discussion, let us take some time to think about how Kinematics fits in with another portion of basic Mechanics, Dynamics (i.e. Newton's Laws and Momentum & Impulse). Kinematics is the art of describing motion. Later, when you progress from Kinematics to Dynamics (i.e. Newton''s Laws and Momentum & Impulse), the concept of force will enter the discussion.

This is a primary conceptual movement in basic mechanics. In Kinematics, you discuss how an object is accelerating. In Dynamics (Newton's Laws & Momentum & Impulse), you discuss why an object is accelerating.

As you progress through this course, carrying out numerous cycles through the material, every time you see the outline of the subtopics of mechanics, you want to keep that in mind as a conceptual organizing principle. Kinematics is about describing motion. Dynamics is about describing interactions.

In Dynamics, you will learn that if an object is accelerating, a force must be acting upon it. The kinematics of an object (its state of acceleration) results from its dynamics (the interactions of the object and other objects in its surroundings). Newton's First and Second Laws are directly concerned with the relationship between motion and force. Every acceleration is caused by a force.

This is a favorite idea for MCAT questions arising from fundamental mechanics. If a particle is accelerating, a force must be acting on it. As soon as you encounter the concept of acceleration, ask yourself 'What is the force?'