Absolute uncertainty

There are two ways to calculate the absolute uncertainty of a result.

1) Absolute uncertainty of a single reading

2) Absolute uncertainty from a range of readings

Watch the video below for a summary and then have a go at the practice questions.  When you are done, move on to the next topic.  And remember – your uncertainty and mean can never be more accurate than your readings so think about your decimal places and significant figures!


1) A student records the time taken for a spring with a mass attached to oscillate once.  They record the time period as 1.24 seconds.

a) The student claims the precision of the measurement is +/- 0.01s.  Are they correct?

b) What would the precision (and therefor absolute uncertainty) actually be?

c) How could the student minimise this uncertainty?

2) The following set of results is obtained for the width of a wooden strip:

2.4cm, 2.6cm, 2.4cm, 2.3cm, 2.3cm, 2.5cm

a) What is the average width of the strip?

b) What is the absolute uncertainty in the width of the strip?



Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s