Coiling/Uncoiling & Compression/Decompression

In this picture, I am serving a tennis ball. During my service, many actions are occurring at once. My jump, to my contact, to my finish. During the jump, i coil into a load up position, and from there explode (uncoil) up to smash the ball. Next, I make contact with the ball. This is an example of compression and decompression. Compression is "the effect, result, or consequence of being compressed," according to Dictionary.com. When i make contact with the ball, it becomes flattened for a split second. It then shoots forward to the other side of the court, decompressing, then compressing again on the other side of the court when it bounces. Decompression is "the act or process of releasing from pressure," according to Dictionary.com as well. Lastly the finish. The finish is the jump of uncoiling, to contact, to landing. The landing suppresses your fall so I don't get injured. My legs continue to act like springs instead of metal beams, a means of protection. (note: the black thing in my right hand is a cast for my ligament tear in the wrist.)

Velocity and Acceleration

Journal 1: In this picture, we can see a glimpse of what Acceleration and Velocity are. Acceleration is "the change in velocity," according to Dictionary.com, or in scientific terms, the equation is Velocity/change in time <-(m/s^2). In this photo, I am just simply walking on a treadmill at a constant speed of 2 (2 is according to the treadmill, unsure of actual speed). Yet when I pressed 3 or anything higher, my acceleration increased, then maintained constant 0 at that newly selected level once adjusted. Until I select a different level, at that moment the acceleration will change. On a graph, acceleration is always horizontal. Velocity is slightly different. Graph wise, a velocity graph can be horizontal, diagonal, but never curved. Velocity is the "rapidity of motion or operation," according to Dictionary.com, but may I also add that direction does matter too, or else it would be speed and not velocity. Velocity is measured by the equation: change in displacement/change in time <-(m/s). Here, my velocity is sadly 0, since my displacement is 0, and I am moving in place. This applies to acceleration as well, that displacement does affect the answer. But say I did move forward, I would be moving in a positive direction for both cases. I would gain Velocity as I moved away from my original point. If i ran at 4mph, I would constantly be moving up the velocity graph, and when I stopped, I would form a horizontal line at that position. Then if i turned 180 degrees and went back at 5mph, my line according to the graph will begin to go towards negative (downward) at a sharper angle (greater slope) than when I was walking forward at 4mph. This is just a simple glimpse at Acceleration and Velocity.