#### Chapter 4 - Dynamics

Newton’s First Law says that an object will persist in its state of motion unless acted upon by a net external force. We will need to apply this law in the GCE A Levels, together with the concept of inertia.

Newton’s Third Law says that if object A exerts a force on object B, then object B exerts an equal but opposite force back on object A. The GCE A Levels requires us to recognise action-reaction pairs, and draw some conclusions based on the knowledge that a reaction force always exists.

In the GCE A Levels, we are introduced to the physical quantity of momentum, and this video explains what momentum is. It is important to understand momentum as Newton’s Second Law explains that the resultant force on an object is directly proportional to its rate of change of momentum, and we will explore that in detail as well.

In the GCE A Levels, one of the most common problems involving Newton’s Second Law is in the analysis of accelerating systems. This video will describe how we use Free Body Diagrams, and the knowledge that the resultant force on a mass is F = ma, to break down and solve such problems.

In the GCE A Levels, a unique application of Newton’s Second Law is in the analysis of fluid streams, such as water jets or air jets. By applying the form F = v(dm/dt), this video will show how to simplify this equation to easily solve problems involving these fluid streams.

This video discusses the quantity known as impulse. In the GCE A Levels, we must understand impulse as the product of an average force and the time it is exerted on an object, but also as the absolute change in momentum of an object.

In the GCE A Levels, we are introduced to one of the conservation laws of physics – the Conservation of Linear Momentum. This video will discuss what COLM is, how it comes about, and discuss some simple examples on when it can or cannot be applied.

There are three types of collisions we must know in the GCE A Levels. These collisions are elastic, inelastic and perfectly inelastic. This video will describe what these types of collisions mean, and also their implications in our calculations.