or

Not ‘great’ data….

Y=mx+c D=4.2t2 g=8.4ms-2

Limited control variables as only one trial tape examined – ideally do more! or you could say that the ttt Voltage was set at 6V throughout the trial If multiple trials then: 50g mass, ttt used, AC 50 Hz frequency, tape size will be your control variables etc Good discussion ideas – E1 gives a justification for why a variable needs to be controlled Justifies the techniques used to reduce friction acting on the ttt data and hence explains why a lower gradient value is obtained. Coordinated group work was a useful accuracy method! The affect of the 50g mass – any change if 100g ?– would drag due to tape friction or tt hammer contact be any different if a heavier or lighter mass were used? Have to assume the ttt was operating at 50Hz so that time between dots was always 0.02s. Can their be variation in Hz between ttt machines? Describes and justifies avoiding the multiple dots at the beginning of the tape that could lead to a zeroing error. Or if the graph doesn’t go through zero uses the idea of a zeroing error that is possible at the beginning of the tape. This error will shift the graph. Discuss the effect of voltage setting on the ttt affect the quality of the dots to adding friction by virtue of contacting the tape.

E2 gives a description of any difficulties encountered when making measurements and how these difficulties were overcome hard to count / distinguish ttt dots as they may have been smudged and states the effect this would have on their results Error associated with reading the dots – to faint – may miss count… E3 gives a reason why there is a limit to either end of the value chosen for the independent variable Squared relationship suggests a small increase in time results in a big change in displacement values and were limited to ~ 1 m of tape, therefore not possible to get 6 sets of 0.1s data if acceleration was close to g value

E4 gives a description of any unexpected results and a suggestion of how they could have been caused and/or the effect they had on the validity of the conclusion. Suggests friction was not constant - msy have being applied later as the tape dragged through – shown by later points being below the LBF… Gradient value significantly different from expected value – due to friction acting on the system, most likely due to… Line of Best Fit has a Y intercept value – mostly due to how first data point is determined… Is it possible to average results? Impossible to draw a suitable line of best fit that is close to the plotted points – explain why large scatter of data occurred – points miss read? Some points not on the LBF, if below the line could be due to miss counting the number of dots E5 compares investigation findings with physics theory (g = 9.8 ms-2) compares experimental g with 9.8 ms-2 discusses that acceleration may not have been constant due to drag forces or friction acting