Download Astrophysics

Astrophysics
Exam Unit II
r3
T2 =
KE + PE = TE
M
v circ =
GM
r
Name___________________________________________
Date ____________________________ Per ______
- GMm
- GMm
2GM
TE =
PE =
KE = 12 m v 2 v esc =
2A
r
r
2 1 
v 2 = GM  − 
 r A
(1 + e)A = R A
(1 - e)A = R p
1
1
1
=
−
S Pf Ps
e=
C
A
M sun = 2.0 E 30kg 1AU = 1.50 E11 m M ⊕ = 5.97 E24 kg G = 6.67 E - 11 Nm 2 / kg 2
1) Suppose a rocket is in orbit around a star that takes 0.18ey to complete. Also the rocket has an average
distance of 0.31AU from that star. What is the mass of that star?
2) Using the Hohmann path how long would it take to transfer from a planet at 2.20 AU to a planet at 0.900 AU.
Assume these planets are in our solar system.
3) A 200. kg spy satellite orbits the earth with a ra = 18000. km and rp= 6800. km . Calculate the following
values at apogee :
A) TE
B) PE
C) KE
4) What is the escape velocity from an asteroid with a mass of 5.5 E 20 kg and radius = 280. km?
5) A rocket is in a circular orbit of the sun at 0.450 AU. To return to earth we need to enter an elliptical orbit
which has an aphelion of 1.000AU . Calculate the ∆V that is needed to change orbits. ( Also, is ∆V + or – ? )
6) In another solar system we want to travel to a planet X from an inner planet Y. The sidereal period of X is
2.30 ey and the transfer time from Y to X is 0.67 ey. What is the window? Be sure to say which planet is ahead?
7) Suppose two planets W and Z in another solar system have sidereal periods TW= 1.95 ey , Tz=2.54 ey.
The window to travel from W to Z occurs when W is 53 degrees behind Z. Calculate how long we must wait to
launch if now W is 96 degrees behind Z.
8) Matching:
___ escape velocity
___circular velocity
___aphelion
___perihelion
___apogee
___perigee
___window
___Hohmann orbit
___bound orbit
___vis viva
A) orbit that has aphelion at one circular orbit and perihelion at
another circular orbit
B) velocity needed so that TE = zero
C) Equation that gives velocity at any point r in an orbit
D) farthest point of orbit from the sun
E) orbit that can never break free from the central body
F) velocity necessary so that PE remains constant
G) closest part of orbit to earth
H) closest part of orbit to sun
I) time when you can launch to meet a planet when you get there
J) farthest part of orbit from the earth
9) Create one problem about something in this unit that is not on this test. THEN answer it correctly.