Am I right?

J

Joyce

New member
Joined
Feb 16, 2006
Messages
26
I'm not sure If I have the right answer, because the question just seemed to easy to answer, could someone please tell me if my method looks correct?


When Dr. Roberta Bondar flew on the space shuttle it lifted off at about 10:00 and then orbited Earth every 90 minutes. At what time of the day did it complete it's ninth orbit?


so I thought I could use the fomrula; tn=a+(n-1)d

a= 10 (10:00)

d=90 (minutes)

n=9 (9th orbit)


t9= 10+(9-1)90

= 730

Therefore it was about 7:30 when she completed here 9th orbit.
 
Couple of things off there.

You have:
a = 10 hours
d = 90 minutes = 1.5 hours
Later, you add minutes to hours and don't adjut the units. You must make up your mind and pick consistent units.

For n = 1, you have t1 = 10 + (1-1)*1.5 = 10 + 0 = 10. That is very curious, since you just blasted off and have not yet completed an orbit. The first orbit completion time is 11:30. Perhaps that would be a better choice of 'a'?
 
yea I figured it involved some kind of a converson, makes alot more sense now! thanks alot tkhunny.

Would this be more relaistic then;

a= 11:30 (11.5)

d= 1.5

n= 9

Therefore;

tn= 11.5 +(9-1) (1.5)

=23.5

So I guess at about 10:30 (12.5 hours later) it would complete it's ninth orbit
 
I'm not sure If I have the right answer, because the question just seemed to easy to answer, could someone please tell me if my method looks correct?

When Dr. Roberta Bondar flew on the space shuttle it lifted off at about 10:00 and then orbited Earth every 90 minutes. At what time of the day did it complete it's ninth orbit?

so I thought I could use the fomrula; tn=a+(n-1)d
a= 10 (10:00)
d=90 (minutes)
n=9 (9th orbit)
t9= 10+(9-1)90
= 730
Therefore it was about 7:30 when she completed here 9th orbit.

Not to be picky but you are forgetting the approximately 54 minutes it takes the orbiter to reach the appropriate altitude with a 90 minute period.
Assuming liftoff is at 10:00AM, [54 + 9(90)]/60 = 14.4 hours making the completion of the 9th orbit occurring at 12:24 AM in the morning of the next day.
 
I'm not really sure where you got 54 minutes from??? Could you please explain. :eek:
 
TchrWill said:
approximately 54 minutes
Click to expand...
I thought about that, but decided 90 minutes was an average of the first 9 orbits.

You're assuming that reaching altitude is a ray from the center of the Earth, dollowed by a hard turn into orbit.

There are quite a few other adjustments that could be made.
 
well, what other adjustments shoud I make? and why 54 min exactly?
 
This site says it takes only 8 and a half minutes ... I realize that's probably LEO, but it doesn't take much more time to change to a 90 minute period orbit.
 
None. Skip it. You're not NASA. You were done when you said 11:30.
 
You must log in or register to reply here.
Top