Posted by y912f on Wednesday, January 7, 2009 at 8:02pm.
assuming that Earth's radius is 6400 km, find the linear velocity of Quito, Equador, a city on the equator. (Use pi=3.1416 and 1.6 km=1 mile).

trigonometry  Damon, Wednesday, January 7, 2009 at 8:08pm
I guess we are to do miles per hour ?
v = omega * r
omega = 2 pi /24 hr
r = 6.4*10^3 km (1 mile/1.6 km) = 4,000 miles
so
v = 4000 miles (2 pi/ 24 hr)
=3333 miles/ hour

trigonometry  drwls, Wednesday, January 7, 2009 at 8:09pm
(2 pi * 6400 km)/(24 hours)
That will give you the answer in km/h. Divide by 1.6 for miles per hour.
Actually, a better conversion factor with five significant figures is 1.6093 km/mile
It makes no sense to have five significant figures for pi and only two for the kmtomiles factor

trigonometry  y912f, Wednesday, January 7, 2009 at 8:13pm
my choices are
2094.4 mph
209.4 mph
1047.2 mph
104.7 mph

trigonometry  Damon, Wednesday, January 7, 2009 at 8:14pm
LOL  the textbook writer is using a calculator with pi on it but not the unit conversions :)

correction  Damon, Wednesday, January 7, 2009 at 8:18pm
v = 4000 miles (2 pi/ 24 hr)
=1047.2 miles/ hour

trigonometry  mysterychicken, Thursday, January 8, 2009 at 11:23am
thnks
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