to accompany
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ORBITAL MECHANICS FOR ENGINEERING STUDENTS
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Howard D. Curtis
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Embry-
Riddle Aeronautical University Daytona Beac
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h, Florida
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, Orbital Mechanics for Engineering Students
Problem 1.1 q
(a)
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A A Axiˆ Ayˆj Azkˆ Axiˆ Ayˆj Azkˆ q
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Axiˆ Axiˆ Ayˆj Azkˆ Ayˆj Axiˆ Ayˆj Azkˆ Azkˆ Axiˆ Ayˆj Azkˆ
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Ax2 iˆ iˆ AxAy iˆ ˆj AxAz iˆ kˆ AyAx ˆj iˆ Ay2 ˆj ˆj AyAz ˆj kˆ
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AzAx k i AzAy k j Az k k q
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Ax2 1 AxAy 0 AxAz 0 AyAx 0 Ay2 1 AyAz 0 AzAx 0 AzAy 0 Az2 1
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Ax Ay2
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2 q
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Az2 q
But, according to the Pythagorean Theorem, A 2 x A 2 y A 2
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2
z A , where A A , the magnitude of
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the vector A . Thus A A A2 .
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(b)
iˆ ˆj kˆ
A B C A Bx
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Cx Cy Cz
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Axiˆ Ayˆj Azkˆ iˆ ByCz BzCy ˆjBxCz BzCx kˆ BxCy ByCx
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Ax ByCz BzCy Ay BxCz BzCx Az BxCy ByCx q
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or
A B C AxByCz AyBzCx AzBxCy AxBzCy AyBxCz AzByCx
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(1)
Note that A B C C A B , and according to (1)
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C A B CxAyBz Cy AzBx Cz AxBy CxAzBy Cy AxBz Cz AyBx
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(2)
The right hand sides of (1) and (2) are identical. Hence A B C A B C .
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(c)
iˆ ˆj kˆ iˆ ˆj kˆ
A B C Axiˆ Ayˆj Azkˆ Bx
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Ay BzC q
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x BxCy BxCy ByCx Cx Cy Cz z BzCyq
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Ay BxCy ByCx Az BzCx BxCz i Az ByCz BzCy Ax BxCy ByCx ˆj
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A B C B C A B C B C kˆ
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AyBxCy AzBxCz AyByCx AzBzCx iˆ AxByCx AzByCz AxBxCy AzBzCy ˆj q q
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x z x y z y x x z y y z
A B C A B C A B C A B C kˆ q q q
Bx AyCy AzCz Cx AyBy AzBz iˆ By AxCx AzCz Cy AxBx AzBz ˆj
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z x x y y z x x y y
B A C A C C A B A B kˆ q q q q
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Add and subtract the underlined terms to get
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1
, Orbital Mechanics for Engineering Students
A B C Bx AyCy AzCz AxCx Cx AyBy AzBz AxBx iˆ
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By AxCx AzCz AyCy Cy AxBx AzBz AyBy ˆj
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B A C A C A C C A B A B A B kˆ
z x x y y z z z x x y y z z
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Bxiˆ Byˆj Bzkˆ q
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A C A C A C C iˆ C ˆj C kˆ A B A B A B
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or
A B C BA C CA B
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Problem 1.2 Using the interchange of Dot and Cross we get
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A B C D
q q q q q q q A B CD q q q q q
But
A B CD C A BD
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Using the bac – cab rule on the right, yields
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A B CD ACB BCAD
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or
A B CD A DC B B DC A
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Substituting (2) into (1) we get q q q q q
A B CD A CB D A DB C
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Problem 1.3 Veloc q q
ity analysis From Eq
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uation 1.38, q
v vo rrel vrel .
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(1)
From the given information we have
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vo 10Iˆ 30Jˆ 50K̂
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rrel r ro 150Iˆ 200Jˆ 300K̂ 300Iˆ 200Jˆ 100K̂ 150Iˆ 400Jˆ 200K̂ q
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Iˆ Jˆ K̂
rrel 0.6
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q 0.4 1.0 320Iˆ 270Jˆ 300K̂
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150 400 200 q q
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