Question

A stopwatch is used to measure how long it takes a sprinter to run 100 meters. this stopwatch measures time intervals to hundredths of seconds. using the stopwatch the timekeeper measures the sprinter’s time as 9.88 seconds. the timekeeper then writes down the sprinter’s time as 9.88 0.005 s ± . what is wrong with this?

Answer 1

First you need to know the smallest counting unit in this case. As this stopwatch measures time intervals to hundredths of a second, the uncertainty should be ± 0.01s (seconds) NOT ± 0.005s. Hence 0.01 is the smallest counting unit in this case. Hence the answer should be 9.88 ± 0.01s.

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