Does air resistance in the pendulum prac affect accuracy or validity? (1 Viewer)

[emilios]

As far as I know, validity refers to how well the experiment tests the aim and hypothesis and it is generally increased by eliminating unwanted variables and making sure you have a tight control of you dependent and independent variables. Accuracy refers to how close your values are to the real value.

So would an external, unwanted force on a bob (air resistance) affect validity (as there is an unwanted variable) or would it affect accuracy (as it changes the value obtained)? Or is it both?

 

[esaitchkay]

You are correct in saying that validity refers to how well the experiment tests the hypothesis. Now, if your hypothesis is regarding the measurement of g, any air resistance due to the string (albeit very minor) would affect the validity of the experiment. However, as you also have mentioned, accuracy refers to the closeness of the measured values to the true values. Now, your true measurement will still be affected by the air resistance. Therefore, air resistance does not concern the accuracy of the experiment.
Errors in measurement will lead to a reduction in accuracy. Hence, things such as light gates (reduce human error) and longer piece of string (reduce relative error) will increase accuracy.