To begin our AP Physics journey here at Falcon Tutoring, it is imperative that we begin with the basics of motion. That includes Unit 1-Constant Velocity. To insure that you can maximize your AP Physics score, stay tuned for a wild Physics series in which we discover the secrets of the Universe using mathematical equations and concepts all from the curriculum of AP Physics 1.
Position, Velocity, Acceleration
We begin our journey with a few vocabulary words that you must be familiar with:
Position: the location of an object relative to a reference point (Vector).
Distance: how far one thing is from another thing; A measure of the space between two things (Scalar).
Displacement: an object's change in position, only measuring from its starting position to the final position (Vector).
Speed: a measure of how quickly an object moves from one place to another. It is equal to the distance traveled divided by the time (Scalar).
Velocity: a measure of how quickly an object moves from one position to another. It is equal to the displacement traveled divided by the time (Vector).
Acceleration: When the velocity of an object changes it is said to be accelerating. Acceleration is the rate of change of velocity with time (Vector).
Motion Map: represents the position, velocity, and acceleration of an object at various clock readings.
Graphs
In order to be successful in Physics, you must be able to decipher graphical displays. Below are some cheat sheets that you can use to identify the motion of an object:
These graphs depict position as a function of time. When an object is gaining no position during a time interval, it is said to have no velocity, aka stationary (Graph 1). When an object is a straight line with a positive slope, the object is said to have constant velocity. It is gaining an equal amount of position per unit time (Graph 2). When an object is travelling with a constant velocity but the slope is negative, the object is simply going towards its initial position, in a negative direction (Graph 3). And lastly, when an object gains a non-constant position per unit time, it is said to be accelerating (Graph 4). However, acceleration does NOT always indicate speeding up. Acceleration refers to an objects change in velocity, therefore it can be slowing down or speeding up.
For each corresponding Position vs. Time graph, there is a Velocity vs. Time graph as well as an Acceleration vs. Time graph. Below are Velocity vs Time graphs with patterns that you will become familiar with as you study motion.
As you can see in the graphs, when an object's velocity becomes a smaller number (lessens), the object slows down. On the other hand, when an object's velocity increases, then it is accelerating in either a positive direction or a negative direction. The sign is determined by looking at the quadrant the line is drawn or the direction the object moves in. If the object moves towards the position it began from, it is in the negative direction and vice versa.
As we approach the last set of graphs, Acceleration vs. Time, it is important to note that for uniform acceleration, the acceleration of a body is constant. We will experience this from time to time until we approach the Simple Harmonic Motion where acceleration is indeed not constant. With velocity vs. time graphs, the slope represents the acceleration of the object. Therefore, if the slope of the corresponding Velocity vs Time graph is positive, we draw the acceleration vs time line in the positive quadrant and vice versa. Below are the 3 Acceleration vs. Time graphs you and I will encounter:
KEY:
Graph 1 represents zero acceleration, indicating that the object could be either moving at a constant speed or not moving at all.
Graph 2 represents a constant positive acceleration, indicating that the object could be speeding up in a positive direction or slowing down in a negative direction since the velocity time graphs would have positive slopes.
Graph 3 represents a constant negative acceleration, indicating that the object could be slowing down in a positive direction or speeding up in the negative direction.
Physics at its Finest
At Falcon Online, we hope to give you the best casual experience possible in prepping for 2020 AP exams. Our next AP Physics article will feature linear kinematics and basic motion equations. Although Physics appears to be the most difficult subject for many, with a deepened understanding of concepts, we believe you can succeed regardless. Thank you for tuning in and we hope to see you next time!
By: Arman Motahar
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