From Rhett Allain: And that is it. Let me put in the following values:
•vs = 7.3 km/s.
•vt = 200 km/s. (yes, I had several values for this but this is the one I am going with)
•tt = 30 seconds.
With these values, I get a distance of about 230 km. So if you are farther than 230 km from the center of the earthquake, you might be able to get a tweet about the earthquake before you feel it.
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.
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.
Bob Beamon's World Record:
Boy Jumping Off 10-Meter Platform:
The Scoring of the Olympic Decathalon: Imaginary Decalathon
"Science Silliness":
Physics of the Gymnastics Giant
High Bar:
University of Michigan
Giant Bar:
Pole Vaulters:
Can Runners Benefit From Drafting?:
Swimming, Power, and Setting Records:
How The Hammer Throw is Like a Particle Accelerator: