Frustrated about a minus in the result (D = RT question)

[Femme_physics]

Homework Statement

1) From two spots, whose distance between them is 25 kilometers, two hikers went towards each other: Hiker A and Hiker B
Hiker A went out at 7:00 AM
Hiker B went out at 7:30 AM

The distance of Hiker A was greater in 1 kilometer per hour than the speed of hiker B (the rates of the hikers are constant). The hikers met at 9:30 AM.

A) Find the rate of each of the hikers.

Homework Equations

D = RT

The Attempt at a Solution

http://img684.imageshack.us/img684/1739/frus.jpg


I'm pretty sure x is 5, but I'm not sure why I'm getting the result in a minus. Should I worry about that?

 

[I like Serena]

1) From two spots, whose distance between them is 25 kilometers, two hikers went towards each other: Hiker A and Hiker B
Hiker A went out at 7:00 AM
Hiker B went out at 7:30 AM

The distance of Hiker A was greater in 1 kilometer per hour than the speed of hiker B (the rates of the hikers are constant). The hikers met at 9:30 AM.

A) Find the rate of each of the hikers.I'm pretty sure x is 5, but I'm not sure why I'm getting the result in a minus. Should I worry about that?

Yes, you should worry about the minus sign.
It would imply that the bikers have to go backward and away from each other.
And that would be rather odd since they're supposed to meet. :)

Your table is fine!

Then what you did is say that the distances the bikers traveled are the same.
But this is not the case.

The problem says that the total distance of both bikers is 25 kilometers.
Can you set up an equation for that?

 

[Femme_physics]

I wrote what you said down on paper and I will reply to you tomorrow evening (i.e. roughly 20 hours from now) after doing some pondering. Thank you ILS!

 

[Omega_Prime]

I may have approached this differently...

D_A + D_B = 25

Where D is just the distance traveled per person and equal to rate*time. I got a positive solution using this method - something for you to take a look at if you'd like.

 

[Femme_physics]

Thank you, Omega Prime! I was ready to write a loooooooong explanation about all the things I tried at work until I read your reply :D Appreciate it! And I appreciate the exercise to my mind and making me think logically about D = RT problems, ILS!

 

[I like Serena]

Thank you, Omega Prime! I was ready to write a loooooooong explanation about all the things I tried at work until I read your reply :D Appreciate it! And I appreciate the exercise to my mind and making me think logically about D = RT problems, ILS!

Hey :)

Yes, that was the equation I had in mind.
And I was kind of looking forward to a loooooooong thread about it.

So did you finish it?

 

[Femme_physics]

Yes, I equated them both to 25

2.5(x+1) +2x = 25
turns out x =5

:)

 

[I like Serena]

Yes, I equated them both to 25

2.5(x+1) +2x = 25
turns out x =5

:)

Yep!

I guess this is not going to be a looooooooong thread after all.

(Note that it is by coincidence that you got -5 earlier! )

 

[Femme_physics]

gotcha ;) oh we'll have it long some other time, for sure :D I like 'em long!

 

[I like Serena]

gotcha ;) oh we'll have it long some other time, for sure :D I like 'em long!

That would bring us to the next stage in the mathgasm cycle: must... learn... more! :)

 

[Omega_Prime]

Yes, I equated them both to 25

2.5(x+1) +2x = 25
turns out x =5

:)

Swish!

 

[Femme_physics]

That would bring us to the next stage in the mathgasm cycle: must... learn... more! :)

Yes indeed ;)

Swish!

Yessss indeed!