A meteoroid is first observed approaching the earth when it is 402,000 km from the center of the earth with a true anomaly of 150. If the speed of the meteoroid at that time is 2.23 km/s, calculate
(a) the eccentricity of the trajectory;
(b) the altitude at closest approach; and
(c) the speed at the closest approach.

Respuesta :

Explanation:

Given that,

Distance = 402000 km

Speed = 2.23 m/s

Angle = 150

(a). We need to calculate the eccentricity of the trajectory

Using formula of eccentricity

[tex]\epsilon=\dfrac{v^2}{2}-\dfrac{\mu}{r}[/tex]

Put the value into the formula

[tex]\epsilon=\dfrac{2.23^2}{2}-\dfrac{398600}{402000}[/tex]

[tex]\epsilon=1.4949\ km^2/s^2[/tex]

We need to calculate the angular momentum

Using formula of  the angular momentum

[tex]h^2=-\dfrac{1}{2}\dfrac{\mu^2}{\epsilon}(1-e^2)[/tex]

[tex]h^2=-\dfrac{1}{2}\dfrac{(398600)^2}{1.4949}(1-e^2)[/tex]

[tex]h^2=-5.3141\times10^{10}(1-e^2)[/tex]...(I)

The orbit equation is

[tex]h^2=\mu r(1+e\cos\theta)[/tex]

[tex]h^2=398600\times402000(1-+\cos150)[/tex]

[tex]h^2=16.02372\times10^{10}(1-e0.8660)[/tex]

[tex]h^2=16.02372\times10^{10}-e13.877\times10^{10}[/tex]....(II)

Equating the value of h²

[tex]-5.3141\times10^{10}(1-e^2)=16.02372\times10^{10}-e13.877\times10^{10}[/tex]

[tex]-5.3141+5.3141e^2=13.877e+16.02372[/tex]

[tex]5.3141e^2+13.877e-21.33782=0[/tex]

[tex]e = 0, 1.086[/tex]

(b). We need to calculate the altitude at closest approach

Put the value of e in equation (I)

[tex]h^2=16.02372\times10^{10}-1.086\times13.877\times10^{10}[/tex]

[tex]h^2=9.53298\times10^{9}\ km^4/s^2[/tex]

Now, using the formula of the altitude at closest

[tex]r_{perigee}=\dfrac{h^2}{\mu}\dfrac{1}{1+e}[/tex]

[tex]r_{perigee}=\dfrac{9.53298\times10^{9}}{398600}\dfrac{1}{1+1.086}[/tex]

[tex]r_{perigee}=11465\ km[/tex]

So, The altitude is

[tex]z_{perigee}=r_{perigee}-r_{earth}[/tex]

[tex]z_{perigee}=11465-6378[/tex]

[tex]z_{perigee}=5087\ km[/tex]

(c). We need to calculate the  speed at the closest approach.

Using formula of speed

[tex]v_{perigee}=\dfrac{h}{r_{perigee}}[/tex]

[tex]v_{perigee}=\dfrac{\sqrt{9.53298\times10^{9}}}{11465}[/tex]

[tex]v_{perigee}=8.516\ km/s[/tex]

Hence, This is the required solution.