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IB/AP Physics 1 - Intro to Kinematics

Abhijit B. Guttikonda

11/15/2022

Find more at Tech Savvy Youth's Blog. The following article is a TSY Blog post for IB/AP Physics 1.

This is the introductory article about Kinematics, and I will be talking about the basics you need to know before moving toward proficiency.

To start, kinematics is defined as the study of motion. When we measure the displacement of an object over its movement or even the velocity of a ball in motion, we work with kinematics, as it allows us to describe the motion of objects in graphs accurately, diagrams, equations, or even words. One important task you must complete throughout this unit is not always to memorize the content but visualize the content, which will be easily replicable in real life.

To be more particular, kinematics involves the use of words such as:

• Distance
• Displacement
• Speed
• Velocity
• Acceleration
• Position

The definitions of these terms are:

• Distance: How much ground an object has covered in its motion
• Displacement: The difference in position between two chosen areas.
• Speed: the distance traveled over the time taken to travel that distance.
• Velocity: the change in position divided by the change in time.
• Acceleration: The change in velocity divided by the change in time.
• Position: The exact location of an object.

Though we have these kinematics terms defined, students frequently need help to differentiate between specific terms such as speed and velocity, velocity and acceleration, or position, displacement, and distance.

Solutions to common misconceptions:

Distance, displacement, and position: Position is generally defined using the exact location of an object with reference to a POI or point of origin. Think of it like this: when you call your parents and ask them to pick up your phone, you would tell them that it is “next to your alarm clock” or “on the right side of your bed,” which is your statement of the position of an object. Distance is just how much ground an object has covered in its motion, whereas displacement is the difference in position between two areas.

Distance and Displacement Model

The pathway in red is your distance, “the path that you would realistically walk if there is no direct path to your destination.” The path in black is the displacement or the immediate difference in position between your starting location and destination. An example is that when walking from Interlake High School to Crossroads, you must take the road even if it is a longer path because going directly through to crossroads means that you would have to cross forestry and the personal property of others (which could get you in a lot of trouble).

Velocity and speed: Speed is how fast something can go, but velocity is how fast it can go along with its direction. For example, if you are moving back and forth really fast, there is no change in position from where you started, so your velocity would be 0. However, since you are moving back and forth, speed will measure the distance you cover while moving back and forth, which leads to speed increasing the more you move back and forth, while velocity stays at 0.

Velocity and Acceleration: Acceleration is the change in velocity over time. This means that if velocity decreases, we have negative acceleration, whereas if it increases, we have positive acceleration. For example, if I was driving on the highway at 60 mph and did not increase or decrease it, we have a value for velocity but no value for acceleration since velocity did not change. However, if I were gaining speed to get from 20 mph to 60 mph, the velocity would change, giving us an acceleration value.

Now that we know our definitions for the terms we will use in kinematics — mechanics, we will work on effective problem-solving approaches in the following article, which involve these quantities.

Signing Off,
Abhijit B. Guttikonda