Physics hardbound books

Physics Basics: An Easy Guide To Understanding Velocity, Acceleration, and Air Resistance

You’ve probably heard before that physics is a hard subject. There are a lot of equations, and it feels like you have to be good at math in order to understand the material. But understanding three simple concepts, velocity, acceleration, and air resistance can help make these ideas easier to grasp. What’s more, this knowledge might even help you with your other studies as well! So if you want to learn some new skills but aren’t sure where or how we offer instruction on these topics. We hope our article will provide an easy introduction for those who need one! 


Kinematic Equations

To understand velocity, acceleration, and air resistance we first need a basic understanding of the kinematic equations. The word “kinematics” means “to describe motion.” Basically, what this means is that if you want to know how fast something moves or how it changes its speed over time, then you would turn to physics for help. Or more specifically, you would use the kinematic equations to determine these things!

The three most important concepts in physics are velocity, acceleration, and displacement, often known as just velocity and displacement because they have units of length/time² since speed is considered a scalar quantity. They can be used interchangeably in many cases without having a negative impact on your results, but you should be aware of the difference. The kinematic equations are:

  • Distance = velocity × time
  • Velocity = acceleration × time + displacement / initial velocity
  • Acceleration = velocity / time²

Notice that these are vector quantities since they have units of length/time². If you take a look at the Kinematic Equations explained above, you can see that accelerating an object means changing its speed by some amount over some period of time, depending on how fast it was moving initially. This makes sense because if an object is currently traveling 5 meters per second and we want to speed it up so it’s moving 7 m/s after 1 second, then it must be the case that its average (vector) acceleration is (7 − 5)/1 = 2 m/s2.


Velocity is really just a measure of motion, and it refers to how fast something is going or how rapidly that object changes position. In most cases, velocity is usually measured in meters per second (m/s). It can also be measured in miles per hour (km/h) if you are in the US since it uses the imperial system for measurements. Velocity can either be positive or negative depending on which way an object is moving. If an object has a positive velocity then it means its speed increased from zero m/s. And if an object has a negative velocity, then it means its speed decreased from zero m/s to become less than zero. But this isn’t always the case. For example, if an object is moving towards a direction and it reaches zero m/s then its velocity becomes negative. We know what you’re thinking: “So does that mean that when an object’s velocity changes from positive to negative or vice versa, there was some sort of collision involved?” Not exactly! What this means is the object changed its speed. 


Acceleration is a change in either speed or direction of a moving body, but not necessarily both. It can be very confusing because words like “accelerate” and “decelerate” sound similar, but now we will explain the difference. Acceleration can be positive or negative just like velocity is, and it’s usually measured as m/s². When you hear someone say that they’ve been “accelerated to a higher speed” or “decelerated to a lower speed” this is what they mean! It might seem counterintuitive at first since both of these phrases mean either speeding up or slowing down, but there’s a subtle difference between them. A change in direction means that an object changes from traveling along one path into another without changing its rate of movement. So if you’re going from point A to point B on the same path, then your velocity would be 0 m/s because you aren’t moving anywhere. But if you changed your path to go from point A into another direction that has a negative velocity then your acceleration would be positive.

Air Resistance

Every object in motion will encounter resistance, but this force usually isn’t noticeable because it doesn’t seem forceful at all! Air resistance is one of the most commonly encountered forms of resistance for objects in motion. It’s so common that we don’t even think about the physics of it when we see moving objects around us like planes, leaves on the wind, or birds in flight. And while air resistance won’t slow down an object like gravity can (even though they are related), it does play an important role when considering velocity and acceleration! To explain why let’s imagine two forces working against one another. One force is gravity pulling down on an object and the other force is air resistance pushing up on it (opposite forces). So which of these two forces will win out? The answer to this question depends entirely on how much mass the object has! If an object weighs very little, then air resistance would be greater than gravity and that means the downward pull of gravity will be slowed by air resistance. If an object weighs a lot or if you put a small amount of matter into a very large space, then the opposite would happen. Gravity wins because there isn’t enough air resistance to slow down its push downwards.


One of the most challenging aspects of studying physics is understanding some of these complicated concepts. But it doesn’t have to be difficult! In this article, we hope you learned how velocity and acceleration are related as well as what air resistance means for an object in motion. Understanding these three topics can help you better understand why a moving object changes its direction or speed at any given time to avoid collisions with other objects around them.