Question

A stopwatch is to be used to estimate the time between the start and end of an event. Event duration might range from several seconds to 10 minutes. Estimate the probable uncertainty in a time estimate using a hand-operated stopwatch that claims an accuracy of 1 min/month (95%) and a resolution of 0.01 s.

Please show DETAILED work please.

How is Uc calculated?

Answer 1

Given Data:

Uo = ±0.005 s (95%)

Uc = ±60 s/month (95 % accepted)

Find:

Ud, UN

Solution:

The plan stage vulnerability will give a gauge of the reasonableness of an instrument for an estimation. At 60 s/month, the instrument precision works out to "- '0.01 s per 10 min of activity. This would recommend a structure stage vulnerability of

Ud = (u5 + u~)1/2 = O.Ols (95%)

for an occasion enduring 10 min versus ±0.005 s (950/0) for an occasion enduring 10 s. Exactness controls the more drawn out term estimation, while goals control the brief span estimation.

In any case, do instrument goals and exactness control the vulnerability in this measurement? The structure stage investigation does exclude the information obtaining mistake involved in the demonstration of truly killing the watch on and. In any case, a first-request examination may be raced to gauge the vulnerability that enters through the strategy of utilizing the watch. Assume a normal preliminary run of 20 attempts of basically killing a watch on and proposes that the vulnerability in deciding the term of an event is assessed by

Ul = 0.15s (95%)

The vulnerability in estimating the length of an occasion would then be better evaluated by condition (5.19).

UN ~ JU5 + UI + U~ = 0.15s (95%)

This gauge will hold for times of up to "- '2 h. Presently a superior choice with respect to whether the watch and system are reasonable for the planned test can be made.