by Chris Peterson » Tue Sep 25, 2012 2:12 pm
JohnD wrote:Don't agree, Chris! I don't think that "the average person has a better feel for 500,000 km/h than they do for 140 km/s".
No one has a mental handle for 500,000kms, unless like you they are an astronomer.
But everyone who can think in kms or can convert them to miles will realise, gosh, my brother John lives in Atlantic City, Marseilles, York or Foggy Bottom(say) and that's only 140kms (90mls) away.
There in one second! That's fast!
I face this situation frequently in discussing meteoritics. A typical meteor is traveling about 50 km/s. In speaking before American audiences, and in the classroom, I find that very few people have a good concept of what this means. Converting to miles is some help, but even 30 miles/s just doesn't make an impression with most people, unless I actually frame it as you do: give a pair of cities and point out that the meteor would travel between them in a second. Most people don't make that connection themselves. But they do seem to get 115,000 mph, even though the number is large. And in giving interviews to newspapers or on TV, I'm always asked what km/s is in miles per hour.
The reality is, most people are generally more comfortable with familiar units, even when the value itself is an unusual one. And that's why I think the best approach is to use both.
[quote="JohnD"]Don't agree, Chris! I don't think that "the average person has a better feel for 500,000 km/h than they do for 140 km/s".
No one has a mental handle for 500,000kms, unless like you they are an astronomer.
But everyone who can think in kms or can convert them to miles will realise, gosh, my brother John lives in Atlantic City, Marseilles, York or Foggy Bottom(say) and that's only 140kms (90mls) away.
There in one second! That's fast![/quote]
I face this situation frequently in discussing meteoritics. A typical meteor is traveling about 50 km/s. In speaking before American audiences, and in the classroom, I find that very few people have a good concept of what this means. Converting to miles is some help, but even 30 miles/s just doesn't make an impression with most people, unless I actually frame it as you do: give a pair of cities and point out that the meteor would travel between them in a second. Most people don't make that connection themselves. But they do seem to get 115,000 mph, even though the number is large. And in giving interviews to newspapers or on TV, I'm always asked what km/s is in miles per hour.
The reality is, most people are generally more comfortable with familiar units, even when the value itself is an unusual one. And that's why I think the best approach is to use both.