HALO & Prof. Splash Video Analysis

1st Video: Top Gear: HALO vs. Ford Velociraptor:

Top Gear. Top Gear(youtube.com). N.p., n.d. Web. 12 Feb. 2013. <[https://www.youtube.com/watch?v=VdIjHlzJlr8 ]https://www.youtube.com/watch?v=VdIjHlzJlr8>.

2nd Video: Mr. Splash:

Youtube.com. N.p., n.d. Web. 12 Feb. 2013. <https://www.youtube.com/watch?v=kvY9jTDTrFg>.

3rd Video: Bright Storm Free-Fall Explained!

Free Fall. Time-saving Fall. N.p., n.d. Web. 12 Feb. 2013. <http://www.brightstorm.com/science/physics/linear-and-projectile-motion/free-fall/>.

Analysis of 1^st and 2^nd videos

In the first video, there is a race between a ford Velociraptor and a HALO jumper. The ford must travel a horizontal distance of 5 miles, and the HALO jumper must travel a vertical distance of 5 miles. The HALO jumper has a terminal velocity of about 120mph. Traveling about 5 miles at 120mph means that the jumper is falling for about .04 hours, or about 2.5minutes. The ford also must complete the course in 2.5 min in order to meet the HALO jumper, as seen in the end of the video. However, the video states that the ford must reach the finish line in 4 minutes. This is the first inconsistency in the video. The video states that the ford must average at about 71 mph. When 4 minutes is converted to hours (about .07hours), the total distance comes out to about 5 miles. One factor that could cause the HALO jumper and the ford to finish neck in neck is the fact that the jumper must pull his shoot at about 2000ft. This would mean that the jumper would be falling at 120mph for 23000ft. 23000ft is equal to 4.6miles. This equates to the jumper falling at terminal velocity for 2.3 minutes. 2.3 minutes off of the 4 minutes the ford needed to complete the course would mean that the jumper was falling the 2000ft for 1.7 minutes. His velocity would equate to about 14mph. The video however stated that the jumper was traveling at an average of 60mph with his chute pulled. Therefore, we believe that this video is not a true simulation due to the inconsistences found. If the video were accurate, the HALO jumper would have reached the finish line much faster than the ford Velociraptor.

The second video deals with a smaller amount of distance to fall than the previous one. It shows a “Mr. Splash” jumping off of a 30 ft. platform taking about 3 seconds to land in a kiddie-pool about 14 inches deep. He is able to not be injured at the end of this video because when he lands he propels himself forwards into the inflated plastic pool in front of him which absorbs much of his momentum therefore allowing him to walk out of the kiddie pool unharmed from his fall. The kiddie pool absorbs 700 kg*m/s from “Mr. Splash’s freefell from 30 ft.  The fall itself is about 3 seconds long but when he jumps up, he creates a period of time where he is not moving down to the pool but accelerating upwards and has less than a second of hang time. This effects the average velocity of the entire fall because he is not accelerating downwards at all time when he is in freefell.  Unlike the first video, Mr. Splash cannot reach his terminal velocity unlike the HALO jumper in the first video. As you could possibly believe, the HALO jumper would not be able to successfully land in a 14 inch pool and able to walk away from it without a scratch as Mr. Splash did from the 30 foot drop opposed to one that is 5 miles. 

Rotational Motion Video Analysis

Veritasium: "Why Do We Get Seasons?":

Bobber Meets Roundabout from Dale Basler on Vimeo.

Roller Carousel




     In the Mckayla Maroney video, the gymnast does a perfect vault. She runs, jumps, and turns while still accelerating. This action allows her to make a perfect jump and turns in the air while landing perfectly. However, momentum is still conserved through this process. Throughout the vault, linear motion as well as rotational motion is applied. Rotational motion consists of a body moving within an axis. In other words, there is a point that the rigid object is rotating or turning on. Referring back to the Mckayla Maroney video, the gymnast receives such a high score on her vault because she has a perfect RIGID body shape that is maintain throughout her experiment, and rigid body rotation is achieved. 



     Compared to the first video, the rotational movement of the diver is much more exaggerated making it easier to be seen. In both situations, the concept of rotational motion and inertia are seen. In his case, Dana Kane, the diver uses the force in pushing off the diving board creating oscillation – a toggling back and forth between two points. The potential energy that was in the diver is transferred into kinetic energy as he begins to bounce on the diving board. In the air, the diver, in this case, tucks his body creating the smallest radius possible. By doing so, he is able to do more somersaults in the air.  When he switches over to a straight position where he is bent only at the hips, his radius is also small allowing him to transition into his somersaults easily. Because he  has a smaller radius, he is closer to his center of mass. His torque, the tendency of a particular force to rotate around a certain axis, increases as he plunges toward the water. T=Fd. As his distance increases so does torque.

     The third video showed more deeply the root of rotational motion: the center of mass. The wine glass represented the center of mass. When an object is at its center of mass, net torque is neglected, and the object is in static equilibrium. As the wine glass hits the broom\stick, the broomstick instantly breaks and rotates. As shown in the video, both pieces of broomstick spin inward towards the point at which the broomstick was broken. The two pieces of the broomstick never touch each other, spinning on their axes. The pieces of broomstick spin inward because they were broken at their center of mass. The center of mass is also the center of rotation.