Precession Of Earth: Spinning On The Axis Environmental .
Precession of Earth: Spinning on the AxisEnvironmental ScienceName: Period: Date:Essential Question: Why is earth’s axis wobbling? Een 1.1.1Instructions: Study the selection and answer the questions.Just like a toy top that wobbles before it falls, the Earth wobbles as itrotates on its axis, the imaginary line that extends through the poles.This wobbling motion is due to the slight bulge at the equator. If youtraced the Earth's axis out into space, you would see the extension ofthe axis slowly tracing a cone shape. The wobble is very slow; it takesthe Earth 26,000 years to trace one complete conical shape. Thiswobbling motion of Earth on its axis is called precession. Because ofprecession, Polaris and Vega alternate as the North Star every 13,000years.Polaris: The Current North StarToday the Earth's axis points within one degree of Polaris, thebrightest star in the constellation Ursa Minor (also called the LittleBear or the Little Dipper). Polaris appears to be in a fixed position inthe sky throughout the year. All other stars and constellations seem to revolve around the North Star.Why isn't the North Star Fixed?Over the course of time, the North Star changes. Right now Polaris is within one degree of true north,but at other times the North Star has been and will again be Thuban (the brightest star in theconstellation Draco), Vega (the brightest star in the constellation Lyra), and Alpha Cephei (the brighteststar in the constellation Cepheus).The North Star changes over time because the direction of the earth's axis changes slowly over time, thisis the result of Precession. Since by definition the North Star is the star most closely aligned with theearth's axis, as the axis moves the nearest star changes too.Precession is the change in the direction of the axis, but without any change in tilt;changes the stars near the Pole; It does not affect the seasons.Nutation is the wobbling during precession; 1/2 one way or the other; period of 18years; due to the Moon; It slightly effects seasons.This type of axis movement is similar to that of a spinning top. As the top slows, the axis of rotationchanges as the top draws out each rotation; that is to say that the stem of the top itself traces out a circularpattern rather than pointing at a single spot or staying mostly still. If you draw an imaginary line of theearth's axis and continue it up to the sky, it will make a similar path. This type of axis rotation is calledprecession.In the case of the earth, precession is caused by the gravitational pull of the sun and the moon. The earth'saxis makes one complete rotation over the course of approximately 26,000 years. If you trace the path ofthe axis in the sky, you will find that Polaris, Vega, Thuban, and Alpha Cephei all fall on or very close toit. So when the earth's axis is at a point on the path near Vega, Vega becomes the North Star whileThuban is the North Star when the axis is near it on the path.Five thousand years ago, Thuban was the North Star. Five thousand years from now, the North Star willbe Alpha Cephei. Seven thousand years after that, it will be Vega. Nine thousand years after that, Thubanwill be the North Star again. At these dates, the various stars will be at the closest to absolute north. For
some time before, the relevant star will be approaching due north and it will be receding for some timeafter the time listed. In these interim times, the North Star is whichever star is closest to north.Answer the following questions1. What is earth’s axis?2. What is precession?3. How long does it take for earth’s axis to wobble into a complete conical shape?
the Earth 26,000 years to trace one complete conical shape. This wobbling motion of Earth on its axis is called precession. Because of precession, Polaris and Vega alternate as the North Star every 13,000 years. Polaris: The Current North Star Today the Earth
Precession is the slow change in the direction of the North Pole. Precession results from torques exerted by the Moon and Sun on Earth’s equatorial bulge. This movement is analogous to that of a tilted top or gyroscope. The period of precession is about 25.8 Kyr. Obliquity is the angle of the tilt of the Earth’s pole towards the Sun.
waste at spinning, improves yarn tensile and evenness characteristics, and enhances fabric appearance and drape. Spinning performance may also improve with combed fiber. MURATA VORTEX SPINNING Like any other spinning system, the MVS performs best with properly prepared fiber. The cotton fibers should be parallel and free of extraneous matter.
Fig 2 type of sheet metal spinning II. PROCESS OF METAL SPINNING Sheet metal spinning is one of the metal forming processes, where a flat metal blank is formed into an axisymmetric part by a roller which gradually forces the blank onto a mandrel& produce the final shape of the spun part. During the spinning process, the
hyperbolic orbits, classical treatment of Rutherford scattering. Rigid body dynamics: Angular velocity and angular momentum as vectors, conservation of angular momentum. Moment of inertia tensor, principal axes. Free precession. Forced precession, gyroscopes. Lamour precession. Elastic media: Hooke’s Law.
fishing line in a spinning reel is exposed, and the index finger is used to release the line and to control the line. The first guide of a spinning rod is large. Various spinning gear is used for casting very light to heavy lures. Line on a spinning rig comes off the spool of line, under the wire bail,
Keywords: Shah Husayn, Punjabi sufi poetry, symbolism, cotton-spinning, weaving, charkha or spinning-wheel Shah Husayn of Lahore is one of the early Punjabi sufi poets whose lyrical and melodious poetic compositions are highly symbolic in nature. He used the vehicle of his verses for dissemination of
0.8 M Earth 1 M Earth 0.1 M Earth Planet Radius (R Earth): 0.95 R Earth 1 R Earth 0.5 R Earth Distance from Sun (DEarth): 0.7 D Earth 1 D Earth 1.5 D Earth Average Surface Temperature: 456 oC 10 oC -95 oC Atmosphere: T
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