Recent comments in /f/mildlyinteresting

hearnia_2k t1_j1ewg7i wrote

Reply to comment by OldTimeyMedicine in Speedometer of a newer Mustang reads "Ground Speed" by egordoniv

Wouldn't it be both? Equal and opposite forces blah blah means if a car drives in one driection then it applies the same force on the ground in opposite direction. So, the ground speed is the different between the speed of the ground in one direction and the car in another direction.

Otherwise the car would have to do some pretty unnecessary calculations to know how much force the car was putting on the earth in the opposite direction, and how much that impacted the speed of the earths rotation etc. Plus the speedo would likely have to show pretty close to 1.3 million MPH?

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hearnia_2k t1_j1evs25 wrote

Reply to comment by JackieMcFucknuckles in Speedometer of a newer Mustang reads "Ground Speed" by egordoniv

But calling it ground speed is not exactly right either.... GPS speed in a straight line should be pretty accurate. Most systems use more accurate positioning satellites than GPS in addition, and they all offer altitude so that can easily be factored in.

Ground speed could be off if the car is drifting for example, since the wheels will be rotating at different speeds.

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JackieMcFucknuckles t1_j1enyel wrote

Reply to comment by eatingmyfist in Speedometer of a newer Mustang reads "Ground Speed" by egordoniv

Wikipedia says it was named for both although Ford credits the guy who liked the planes as the person who came up with the name.

One of the people who suggested the name apparently liked the planes, but someone in marketing also suggested the name because he liked the horses. I assume the latter is how it got it’s badges.

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JackieMcFucknuckles t1_j1emxsz wrote

Reply to comment by egordoniv in Speedometer of a newer Mustang reads "Ground Speed" by egordoniv

GPS speed and Ground Speed don’t always match. That would be really the only other option, but it’s negligible.

Example: a car traveling over mountainous terrain will have a higher ground speed than gps speed since the gps speed is only accounting for position and not elevation. Traveling up a mountain and back down the other side is a longer ground distance (sum of 2 sides of a triangle is always longer than the length of the 3rd side) than the straight line distance if there were, say, a tunnel through the mountain.

It’s really not useful data though because it’s usually a negligible difference.

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