You are driving along a straight highway. Your very accurate cruise control keeps you at exactly 60 mph. Your GPS device is programmed to take you along this route to point B. At point A it tells you you have exactly 60 miles to go. Similarly, you have measured the distance from A to B on a very accurate large-scale map and gotten exactly 60 miles. You start a very accurate stopwatch at point A. When you reach B, the stopwatch, instead of reading 1 hour, reads 1 hour and three seconds. How can this be? (I will eventually give my answer in this thread.)
Hills?
tire wear/pressure?
Curvature of the Earth?
I thought of ‘variable factors’ but “very accurate cruise control” would compensate for the various resistant forces, wouldn’t it?
I was thinking it has something to do with Geographic Variations in Positioning Errors of satellite to GPS unit or something but 3 sec per 60 min/60 miles is a lot.
No, I mean going up and down slopes adds some distance.
It’s those damned neutrinos again, isn’t it?
Agreed.
Or Higgs Boson…
I assumed “a straight highway” as a level straight highway.
The inability of a car to drive in a perfectly straight line?
That extra three seconds is 264ft, or 88 yards, at 60 mph. What’s that tell us?
If this map is one that, like most, renders the surface of the earth as a plane, then note that it can be fully accurate only in one dimension.
Yes, this is the answer I intended. I didn’t think someone would get it so quickly. If the road is hilly, then you actually have to travel more than 60 miles. I noticed the other day that, even with my cruise control on, my GPS would display a slightly lower speed than my speedometer when I was going UP or DOWN a hill. Apparently the GPS only calculates your speed as if you were travelling on a flat terrain, in terms of latitude and longitude; the same is true with a flat map.
Both maps and GPS receivers take this into account. So, for example, if you ask your GPS receiver to tell you the straight-line distance from NYC to LA, it gives the length of a great circle route across the surface of the earth, not the distance of a tunnel through the earth.
That would be roughly an extra three miles of travel. In my old age my ability to solve pythagorean equations is letting me down, but I think those would be some significant hills.
Which “that” would be 3 extra miles? If you mean the OP’s problem, he said the clock ran 3 *seconds *long. At 60 mph, it’d take 3 *minutes *to chalk up 3 extra miles. Ref post #11 for more.
I’d say your trig is fine; your units awareness could use a touch up though 
Or are you talking about the extra distance for a great circle between NYC & LA per Xema?
More like my reading comprehension.
::tail between legs::
That slowing to a stop at point B is going to add more time to the total travel time. Assuming, that is, you aren’t blowing through point B at 60 mph like you’re in a drag race.
Who said anything about point B being a destination? Unless told otherwise, I’d presume the driver was continuing on to points C, D, and E without stopping.
How about the time it takes to get up to 60mph starting from a standstill at point A? You can’t start at point A and instantaneously be going 60mph.