Does this answer deserve full marks? (1 Viewer)

[sadpwner]

Here's the question:
Outline a first-hand investigation that could be performed to measure a value for acceleration due to gravity.

This is also the same question from the 2012 hsc, but ours was a 2 mark rather than 3.

Here's my answer:

Set up a pendulum on a retort stand. Accurately measure its length, l, from the point of suspension to the centre of the pendulum bob. Allow the pendulum to swing back and forth 10 times through an angle of about 5 degrees with the vertical and measure the time wit ha stopwatch. Calculate the average for 10 swings by dividing the total time by 10, which will find the period T. Then calculate g using T=2pi sqr(l/g).

This is also the same answer provided by the Physics past hsc paper worked solutions compiled by Catherine Odlum. Accordingly to my teacher, if you don't mention the graph line of best fit, you lose 1 whole mark.

 

[Fizzy_Cyst]

Must mention how you graph it (which variables do you plot?), find gradient of line of best fit, rearrange pendulum equation to include gradient of the line of best fit.

By taking the line of best fit, you are eliminating systematic error from your results, whereas by using your method (individual set of results for 1 length of pendulum) systematic error is included and this will influence your determination of 'g'.

I 100% agree with your teacher.

Take marking schemes with a grain of salt, unfortunately they are often not the be all and end all, especially Success One type books, they often contain answers which are either partially or ENTIRELY incorrect and would not receive full marks.