"Extended Course: Breaking through the "Three Difficulties" in Satellite Operation Issues" Gravity and Space Navigation PPT High-Quality Courseware

Description

"Extended Course: Breaking through the "Three Difficulties" in Satellite Operation Issues" Gravity and Space Navigation PPT High-Quality Courseware

Knowledge expansion

Expansion point 1: Satellite orbit change problem

1. Handling of satellite orbit changes

There are two situations of "orbit change" of satellites in motion: centrifugal motion and pericentric motion. When the universal gravitation exactly provides the centripetal force required for the satellite to move in a circular motion, that is, when GMmr2=mv2r, the satellite moves in a uniform circular motion; when the speed changes suddenly at a certain moment, the required centripetal force will also change suddenly, but the universal gravity does not change at the moment of the sudden change.

(1) Braking orbit change: The speed of the satellite becomes smaller, so that the gravitational force is greater than the required centripetal force, that is, GMmr2>mv2r. The satellite performs pericentric motion and the orbit radius will become smaller.

(2) Accelerated orbit change: When the speed of the satellite increases, the gravitational force is smaller than the required centripetal force, that is, GMmr2

2. Orbital change process

(1) In order to save energy, launch the satellite into circular orbit I on the equator in the direction of the earth's rotation, as shown in the figure.

(2) The ignition accelerates at point A (perigee). As the speed increases, the gravity is not enough to provide the centripetal force for circular motion in orbit I, and the satellite moves centrifugally and enters elliptical orbit II.

(3) Ignite again at point B (apogee) and accelerate into circular orbit III.

3. Analysis of various physical quantities in the orbit change process

(1) The linear speed v at the "tangent point" of two different orbits is not equal. In the figure, vⅢ>vⅡB, vⅡA>vⅠ.

(2) The linear velocities of perigee and apogee are not equal in the same elliptical orbit, and the linear velocity gradually increases from apogee to perigee.

(3) The linear speed v on two different circular orbits is not equal. The larger the orbit radius, the smaller v. In the figure, vⅠ>vⅢ.

[Examination Cases]

[Example 1] (Multiple choice) When launching a geosynchronous satellite, first launch the satellite into a low-Earth circular orbit 1, then ignite it to run along an elliptical orbit 2, and finally ignite it again to send the satellite into synchronization Circular Orbit 3. Orbits 1 and 2 are tangent to point Q, and orbits 2 and 3 are tangent to point P, as shown in the figure. When the satellite is operating normally in orbits 1, 2, and 3 respectively, which of the following statements is correct ()

A. The speed of the satellite in orbit 3 is greater than the speed in orbit 1

B. The angular velocity of the satellite on orbit 3 is less than the angular velocity on orbit 1

C. The acceleration of the satellite when it passes point Q on orbit 1 is greater than the acceleration when it passes point Q on orbit 2

D. The acceleration of the satellite when it passes point P on orbit 2 is equal to the acceleration when it passes point P on orbit 3.

[For training 1] (Multiple choice) As shown in the figure, during the launch of a geosynchronous satellite, the satellite first enters the elliptical orbit I, and then changes the satellite speed at point Q to enter the geosynchronous orbit. Ⅱ, then ()

A. The launch speed of the satellite must be greater than 11.2 km/s

B. The satellite’s operating speed in synchronous orbit II is greater than 7.9 km/s

C. In an elliptical orbit, the satellite’s speed at point P is greater than its speed at point Q.

D. The satellite moves from orbit I to orbit II by accelerating at point Q.

Expansion point 2: Comparison of physical quantities of synchronous satellites, near-Earth satellites, and objects on the equator

1. Similarities

(1) They all perform uniform circular motion with the center of the earth as the center.

(2) Geostationary satellites have the same angular velocity as objects on the equator.

2. Differences

(1) Differences in centripetal force

Both synchronous satellites and near-Earth satellites are provided with centripetal force by gravity, GMmr2=mv2r; while the centripetal force (very small) of objects on the equator that make circular motion with the rotation of the earth is a component of gravity, GMmr2≠mv2r.

(2) Differences in centripetal acceleration

[For training 2] There is an object on the equator of the earth that makes a circular motion with the rotation of the earth. The centripetal force is F1, the centripetal acceleration is a1, the linear velocity is v1, and the angular velocity is ω1; it makes a circular motion around the surface of the earth. The centripetal force of the artificial satellite (the height is ignored) is F2, the centripetal acceleration is a2, the linear velocity is v2, and the angular velocity is ω2; the centripetal force of the geostationary satellite is F3, the centripetal acceleration is a3, the linear velocity is v3, and the angular velocity is ω3. The gravitational acceleration on the earth's surface is g, and the first cosmic velocity is v. Assuming that the three have the same mass, then ()

A.F1＝F2＞F3 B.a1＝a2＝g＞a3

C.v1＝v2＝v＞v3 D.ω1＝ω3＜ω2

Keywords: PPT courseware for high school physics compulsory course 2 is free to download from the People's Education Press, PPT download to break through three difficulties in satellite operation issues, Gravity and space navigation PPT download, .PPT format;

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Update Time: 2024-09-30

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