<PRE><B>Question 793137</B>
The rails of a railroad are 30 feet long. As a train passes over the point where the rails are joined, there is an audible click.
 The speed of the train in miles per hours is approximately the number of clicks head in how many seconds?
:
Each click indicates the train has traveled 30 ft
1 click per second is: 30 ft/sec; which is {{{(3600*30)/5280}}} = 20.45 mph
therefore
Approx 
 20 mph = 20 clicks in 20 seconds
then
 30 mph = 30 clicks in 20 seconds
 40 mph = 40 clicks in 20 seconds
 50 mph = 50 clicks in 20 seconds
 60 mph = 60 clicks in 20 seconds
:
Count the number of clicks in 20 seconds to get the speed in mph
;
:
See if that checks out at 60 clicks
Find the ft/sec
{{{(60*30)/20}}} = 90 ft/sec
Find mph
{{{(90*3600)/5280}}} = 61.36 mph, close enough
 

</PRE>