All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Just Math
Intergalactic Journey (Posted on 2005-05-05) Difficulty: 2 of 5
Captain Kirk’s starship leaves Earth for Planet X at the same time Marvin the Martian’s starship leaves Planet X for Earth. Each ship travels at a constant velocity, but one is faster than the other. After meeting and passing, Kirk requires 22.5 hours to reach Planet X, while Marvin requires only 10 hours to reach Earth. Exactly what total time did each starship require for its interplanetary journey? Assume stationary planets.

Credit for this problem goes to Cliff Pickover

  Submitted by nikki    
Rating: 3.0000 (4 votes)
Solution: (Hide)
Call Kirk’s speed u, and Marvin’s speed v. Since they both left at the same moment, and then meet each other along the way, they both traveled the same amount of time over this portion of the journey. Call this amount of time t.

Therefore we have the following distances:

Dist. travelled by Kirk before meeting = tu
Dist. travelled by Marvin before meeting = tv

Dist. travelled by Kirk after meeting = 22.5 hours * u
Dist. travelled by Marvin after meeting = 10 hours * v

Notice:
Dist. travelled by Kirk before meeting = Dist. travelled by Marvin after meeting
So tu = (10hr)v
Dist. travelled by Marvin before meeting = Dist. travelled by Kirk after meeting
So tv = (22.5hr)u

tu = (10hr)v
t = (10hr)v/u

tv = (22.5hr)u
v = (22.5hr)u/t

t = (10hr)v/u = (10hr)*((22.5hr)u/t)/u = (225hr2)/t
t2 = 225hr2
t = 15 hours

So Kirk’s ship took 22.5+15 hours = 37.5 hours total.
And Marvin’s ship took 10+15 hours = 25 hours total.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
QuestionRelativity.Vee-Liem Veefessional2010-05-07 13:27:11
No Beastie BoysLarry2005-05-20 17:03:28
SolutionOr, View It This WayCeeAnne2005-05-08 06:22:24
SolutionZoom-a-zoom-zoomJer2005-05-05 18:00:24
SolutionAnother solutionJurgen2005-05-05 13:02:38
re: SolutionPenny2005-05-05 13:02:16
Solutionre: Solution with modificationLeming2005-05-05 11:41:44
SolutionSolutionPenny2005-05-05 10:28:09
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (16)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2024 by Animus Pactum Consulting. All rights reserved. Privacy Information