Question

Time intervals measured with a stopwatch typically have an uncertainty of about 0.2 s, due to human reaction time at the start and stop moments. What is the percent uncertainty of a handmaid measurement of (a) 5s, (b) 50s, (c) 5 min

Answer 1

a) 8%

b) 0,8%

c) 0,1333%

Explanation:

To calculate percentage uncertainty, you need to take the lowest possible value you can get (4,8s using a) as an example) and calculate the percentage of that.

(4,8/5)*100= 4%

This however is not the end, because there is the possibility of getting 5,2s as an answer. Hence the answer of 4% needs to be doubled.

Therefore, the answer for a) is (4%*2)= 8%

The same principle can be applied to figure out the answers for b) and c). In c), remember to convert 5 minutes to 300 seconds to avoid confusion between units of time.