Category Archives: Algebra 1

Ping Pong Parabolic Motions

Ping Pong Analysis

video here!

My parabola for this video was based on a Ping-Pong hit. The hit was a positive parabola because the vertex was a maximum and the parabola starts low and shoots up in the air and comes back down. Because the distance travelled was very small, I used centimeter units for tracking the a, b, and c digits. The A digit stands for the width of your parabola. For instance my parabola was slightly narrow, so the A digit was -349.2 centimeters or around -3.5 meters. The C digit stands for the y-intercept of your parabola. For my y-intercept, I didn’t start at the height of the table, but a bit taller. So the C digit was placed at 25.59 centimeters, or around 0.26 meters. The B digit stands for the vertex, or the highest point of the parabola. The shot I made for Ping-Pong was fairly high; therefore, my vertex was pretty tall. My B digit was set at 263.9 centimeters, or around 2.64 meters.

 

If you were to put that all together in a quadratic equation – which is the equation we will be using to solve the parabolic motion – it would be easier to round up the unit of measurement to meters. Leaving us with the digits -3.5, 0.26, and 2.64. The equation would end up being y = -3.5(t2) + 2.64(t) + 0.26. In this equation we can sub in the time from any part of the equation and find out the y point.

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In our daily lives, there are many different examples of parabolic motions. For example when you drink water from a water fountain, when the water comes out, it squirts in a parabolic motion. The y-intercept being where the water is erupting from, the vertex is when the water reaches the highest point, and the A digit being however wide the parabola of the water is. Another very common example of parabolic motions in our daily lives is throwing and catching a ball. The motion it makes when it leaves your hand all the way until it reaches the other persons hand is also a parabolic motion; however, most parabolas in our lives are restricted. A restricted graph means there is a start and stop that unlike other graphs do end.

DIY Forensics 101 – Bones

We often wonder how those forensic shows work, and how do they determine whom each person was. Now I have some answers. Forensics often include deceased human in them, and they use forensic equations to figure out the height of the person depending on their limb bones. If you’re wondering about how the different genders and races effect the equations, you’re about to figure out. For each race, there is a different equation; there are the African Americans, the Caucasians, and the Asians. In other words, if you were to measure the length of a limb, you can figure out the height of that person, only if you knew their race and gender. How well do these equations work? Very well. You can tell because usually in a crime scene, there will be some kind of trace left behind, most likely a body part, and using forensic equations you can figure out the height. Using the height you can match it to a missing person report, and figure out who the limbs belong to.

There is a con, what if something goes wrong? Well first lets see what could go wrong. There is a chance of mistaking the race or gender, and the whole equation could be off. Maybe the bone is missing a chunk and you cannot use the proper equation, or you could use the – for example – ulna bone equation, when the bone was actually the tibia. Also the equations are not always 100% accurate, sometimes not even 90%. But the bright side is they could improve these equations and actually make it more specific. They can maybe specify the different races a bit more, for example instead of Caucasians; they could do Americans, and Europeans, making the accuracy a bit higher.

Lots of cases may still remain a big mystery to forensic scientists, and there is a lot we still could discover in forensics. But that’s all I know for now. Someday maybe we could all solve our own cases, and have our own special on solving forensic cases.