(no subject)
Back at Greenbriar West elementary school, my classmates and I learned a song in music class about the metric system. The song taught me that the then-federally-mandated speed limit of 55 miles per hour was equal to 88 kilometers per hour.
As it turns out, this 5/8 ratio is both portable and quite accurate. And were it not for my usual morning run, I would leave it at that.
The running path around my neighborhood measures between .77 and .78 miles. Thus, my usual four laps makes for 3.1 miles, or about 5 km.
3.1? Why, that's almost π. So 1 km is roughly π/5 miles. How useful is that? It means that a circle with a diameter of 1 mile has a circumference of slightly over 5 km, for one.
But there are plenty of well-measured 5 km routes, you say. How about this, instead?
You need to measure a distance on a curved path depicted on a map. You prefer to use kilometers, but the map is scaled in miles. Find a coin (or better yet, a washer) with a diameter close to the scale distance of one mile. Gently roll it along the curved path and count the number of revolutions. Multiply by five to get kilometers.
As it turns out, this 5/8 ratio is both portable and quite accurate. And were it not for my usual morning run, I would leave it at that.
The running path around my neighborhood measures between .77 and .78 miles. Thus, my usual four laps makes for 3.1 miles, or about 5 km.
3.1? Why, that's almost π. So 1 km is roughly π/5 miles. How useful is that? It means that a circle with a diameter of 1 mile has a circumference of slightly over 5 km, for one.
But there are plenty of well-measured 5 km routes, you say. How about this, instead?
You need to measure a distance on a curved path depicted on a map. You prefer to use kilometers, but the map is scaled in miles. Find a coin (or better yet, a washer) with a diameter close to the scale distance of one mile. Gently roll it along the curved path and count the number of revolutions. Multiply by five to get kilometers.