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Physics Density Prac write up
Raw Data:
Mass of different weights
Trial 5g +0.01 /g
Trial 10g +0.01 /g
Trial 20g +0.01 /g
Trial 50g +0.01 /g
Trial 100g +0.01 /g
5.12 10 19.90 50.42 99.99
5.11 9.99 19.89 50.45 99.98
5.12 10.01 19.89 50.45 99.98
5.11 10 19.90 50.45 99.98
5.12 9.99 19.90 50.45 99.98
Volume of different weights
Trial 5g +1 / ml Trial 10g +1 / ml
Trial 20g +1 / ml Trial 50g +1 / ml
Trial 100g +1 / ml
1 2 4 5 14
1 1 2 8 11
1 2 2 6 14
1 1 2 8 12
1 1 4 6 12
Example Questions:
Average of mass 5g
5.12+5.11+5.12+5.11+5.125
=5.12 g
Average of volume 5 cm3
1+1+1+1+15
=1ml
Converting to SI units
Changing grams to kilograms: / 10000
5.121000
=0.00512
Changing cm3 to m3 / 1000000
11000000
=0.0000001
Uncertainty:
I used standard deviation from the mean to calculate the uncertainties for the processed data for example: in 5g the standard deviation is 0.01g and therefore this is its uncertainty
Processed Data:
Average Mass in grams
Trial 5g +0.01 /g
Trial 10g +0.01 /g
Trial 20g +0.01 /g
Trial 50g +0.02 /g
Trial 100g +0.01 /g
5.12 9.99 19.99 50.44 99.98
Average Volume in millilitres
Trial 5g +1 / ml Trial 10g +1 / ml
Trial 20g +1 / ml Trial 50g +1 / ml
Trial 100g +1 / ml
1 1.9 2.8 6.6 12.6
SI units
Average Mass in Kilograms
Trial 5g +0.00001 /kg
Trial 10g +0.00001 /kg
Trial 20g +0.00001 /kg
Trial 50g +0.00001 /kg
Trial 100g +0.00001 /kg
0.00512 0.000999 0.01999 0.05044 0.09998
Average Volume in Litres
Trial 5g +0.000001 / L
Trial 10g +0.000001 / L
Trial 20g +0.000001 / L
Trial 50g +0.000001 / L
Trial 100g +0.00001 / L
0.000001 0.0000019 0.0000028 0.0000066 0.0000126
Graphs:
0 2 4 6 8 10 12 14 160
20
40
60
80
100
120
Uncertainty of the density of Brass
Volume/cm3
mas
s/g
Max Slope Trend line: y = 9.90208333333333x -14.7841666666667
Min Slope Trend line: y = 6.96029411764706x + 5.22
0 2 4 6 8 10 12 14 160
20
40
60
80
100
120
Density of Brass
Volume/cm3
mas
s/g
Trend line: y = 8.26111111111111x -3.99611111111111
Conclusion:
Our results show that the density of the Brass we were testing is 8.2 + 1.3 g/cm3, we can see this as density is equal to gradient in the graph. The known value of the density of Brass is between 8.2 – 8.75 g/cm3, this means that with our uncertainty we support the theory for the known density of Brass. An observation that was noticed is that although all of the weights were almost identical in mass and shape, the volumes did differ more towards the heavier masses. The evidence of error we have from the graph is that the y intercept does not go through the origin which means that there must be some form of systematic error. The main sources of error are the equipment as the masses of the predetermined weights were not accurate and consistently inaccurate and the volume measurements could be inaccurate as the uncertainty is 1 mL which is very large when that is sometimes a 100% uncertainty. Ways to eliminate the errors would be to use more accurate measuring cylinders so that the volume is closer to the actual value which could make our measurements closer to the accepted value.
