Introduction
Welcome to the FiveHive article for Unit 4.1 of AP Physics 1!
This article will cover all the basics needed to understand linear momentum, which will be expanded upon in later topics. It must be noted that momentum is assumed to be linear if not specified, which is the main focus of this article.
As usual, we will only cover the topics included in the CED for unit 4.1.
Linear Momentum
Momentum is understood as the combination of mass and velocity, connected by multiplication. This means that both mass and velocity are directly correlated with momentum using the equation . This also means that momentum is applied in the same direction as the velocity vector and that the net momentum of a system is just adding up all the individual momentum vectors.
This is most commonly used in two contexts: explosions and collisions. Collisions are when two objects hit each other, while explosions occur when an internal force causes separation between two objects in a system. For example, a spring being unlocked and pushing two carts apart would also be classified as an “explosion.” Since these actions occur in a single brief instance, external forces are treated as negligible for that brief period of time, so the momentum of the system is equal before and after the collision or explosion. At the same time, we only observe objects before and after the collision and not during, so you can simplify the objects involved into their attributes and treat them like other objects during the course as just a single point at the center of mass.