Have you ever seen this in your mirror?
Did you know that
when you change tires on your vehicle that your speedometer
reading may change?
Are you aware that many speedometers are inaccurate, even in a brand new car?
Below is an easy method to help you determine if, or how much your speedometer may be off:
1. Maintain a
consistant speed of 55 miles per hour (according to your
speedometer) for at least 1 mile.
2. Using a watch with a second hand or a stop watch determine how many seconds it takes to travel the
mile indicated by the markers.
If it takes this
many seconds to travel the measured mile
then you are traveling this fast irregardless of what the speedometer reads.
To be even more precise you should time yourself over a 10 mile stretch to eliminate any slight variations in the mile markers.
Remember too, that speedometer error is percentage rather than a set amount of miles per hour over the entire spectrum of the speedometer. For example, if your speedometer is off by approximately 10% over the entire range of the speedometer and not 5 miles per hour over the entire range. At 30 miles per hour the error would still be 10% but would only be 3 miles per hour (10% of 30 miles per hour).
if you are traveling X number of MPH indicated in column A, then you are traveling X number of feet per second indicated in Column B.