Is answer in BMW book for problem 4.3 wrong?

 

Proof that book problem answer is wrong:

 

Since r0 and v0 are perpendicular, then satellite must be at aporigee or perigee.

 

But ro  = I + J,   hence |ro| = sqrt(2)

and vo  = 2K       hence |vo| = 2

 

          v^2       u

Energy = ------ - ----

2                                r

 

Hence Energy (calculated at perigee) = 4/2 – 1/sqrt(2) = 1.2928932

 

Since E>0, this is a hyperbola. Then must be a perigee.

 

             u

Energy = - -----                          ---(1)

            2a

 

To find ‘a’, Plug Energy in (1), and noting that u=1, we get

 

                1

1.2928932 = - -----        

                2a

 

hence   a =  -0.3867295  DU       

 

              | I  J  K |

h = r0 x v0 = | 1  1  0 | = I (2) – J (2)

              | 0  0  2 |

 

hence h = sqrt(4+4) = sqrt(8)

 

          h^2

Now, p = ----  = h^2

           u

 

Hence p = 8          

 

                          p

To find e, from  rp = --------------- 

                        1 + e cos(0)

 

(I can also use  p=a(1-e^2) to find e).

 

since rp = r0 = sqrt(2), then  1+e=8/sqrt(2)

 

e = 8/sqrt(2) – 1  =   4.656854

 

Now we can find r when satellite traveled 60 degree.


 

        p                       8

r = ---------------  = ----------------------  = 2.4035377 DU

     1 + e cos(60)      1 + 4.656854 cos(60)

 

 

Now I find v when satellite traveled 60 degrees

 

From

 

    v^2     1

    ---  - ---  = Energy

2                        r  

 

But we found Energy and r from above, and since Energy is constant, so solve for new v

 

v^2 = 2 (1.2928932 + 1/2.4035377)

 

v^2 = 3.417893173

 

v = 1.84875449  DU/TU

 

Now, the book gives this answer as to the velocity:

 

v  = -0.348 I – 0.348 J + 1.5 K

then v = 1.57867286  DU/TU

 

as you can see, this answer does not agree with my calculation.

I do not see where I am going wrong. Is the book wrong or right?