Question

Can someone help me? My homework is due on Friday and I really need help. Does the speedometer on a car give you the instantaneous or average speed? If you wanted to know the average speed of this car (and you were inside the vehicle) at the end of its trip, but you did not know its total distance or the total time the trip took, how might you be able to estimate the average speed, if at all? If you wanted to make an even better estimate, what would you change in this method?

Answer 1

Answer:

• "instantaneous"
• sample the speed at regular intervals and compute the average
• use more samples and/or more regular intervals and/or use a weighted sum that approximates the curve between readings.

Explanation:

A speedometer is designed to give an approximation of instantaneous speed. It is an average over a short time interval, typically less than a second or two.

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If you have only the speedometer as reference, you need to write down its speed reading on several occasions, roughly equally-spaced in time. The average of these readings will be an approximation of your average speed.

To get a better average, shorten the intervals and make them more evenly-spaced. You can also compute various weighted averages of these speed readings.