I drive at an average speed of 30 miles per hour to the railroad station each morning and just catch my train. On a particular morning there was a lot of traffic and at the halfway point I found I had averaged only 15 miles per hour. How fast must I drive for the rest of the way to catch my train?

Question

antiprime · Answer

i think i know the anwser

welshfella · Answer

what do you think it is?

antiprime · Answer

The train is just about to leave the station and there is no way I will be able to catch it this time. 



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ganeshie8 · Answer

this is really a very interesting question !

antiprime · Answer

yes ik and its math related

igreen · Answer

You would have to go double the speed since you were only going half the speed from half way..right?

ganeshie8 · Answer

basically you're trying to find $v$ that satisfies below equation : 
$$\dfrac{x/2}{15} + \dfrac{x/2}{v} = \dfrac{x}{30}$$

antiprime · Answer

yes but on original days he almost misses it

ganeshie8 · Answer

solving gives $v = \infty$

antiprime · Answer

and u cant achive that speed

igreen · Answer

If the car is like the car you have in your picture, you shouldn't have to worry about speed :P

antiprime · Answer

lol @iGreen

ganeshie8 · Answer

you can still catch the train if you know special relativity

antiprime · Answer

well we are assumig the person doesnt

ganeshie8 · Answer

you can go at some appropriate speed such that the remaining distance shrinks by the required amount so that you catch the train at exact time

antiprime · Answer

how can he avrage 30 mph tho

ganeshie8 · Answer

heard of space contraction and time dilation before ?

ganeshie8 · Answer

hey we cannot achieve if we stick to old newtonian physics

i think we will have some hope if we use special relativity..

antiprime · Answer

kinda

antiprime · Answer

this is still complicated

ganeshie8 · Answer

the simple answer to you question is impossible yeah :)

antiprime · Answer

if u can time warp then mabye lol

ganeshie8 · Answer

space contraction doesn't help here as your velocity relative to earth in radial direction is 0

antiprime · Answer

true

ganeshie8 · Answer

oh no, it should still apply...

antiprime · Answer

@welshfella it still can happen some way

anonymous · Answer

http://openstudy.com/study#/updates/570cff8ee4b03d42c8058ba3

anonymous · Answer

this question doesn't need 12 people answering it

anonymous · Answer

try helping someone else

welshfella · Answer

yes? 
perhaps thers something wrong with my calculations then

antiprime · Answer

it still can happen if we have the right automobile

welshfella · Answer

ah yes  the Batmobile!!!!

antiprime · Answer

anyways thxs guys for helping i gtg  <3 U GUYS

welshfella · Answer

yw  - interesting question...

ganeshie8 · Answer

you can't catch the train because it has already started and traveling to past is impossible as far as we know

mathmale · Answer

If you seriously want to solve this problem (or to prove that it can't be solved), please represent your unknown quantities.  Regardless of the speed traveled, the distance d from home to station is a constant.  The commonly used formula for distance is d=rt, where r is the rate of travel (and could be the average rate of travel).

Is there any particular speed that in combination with 15 mph would result in this commuter's reaching the station just in time to catch the train?