Research laboratory work in physics

MEASUREMENT AND PRECISION OF PHYSICAL QUANTITIES

Situation description

It is possible to determine the size and volume of various objects both by direct and performed measurements. The obtained results will vary, it also depends on the accuracy of the measuring instruments used.

Task

Using a tape measure and a measuring cylinder, determine the volume of a given body and the accuracy of the estimated results by calculating the absolute error and the relative error.

Work accessories and substances

Tape measure, measuring cylinder (measuring glass), rectangular parallelepiped (to sink in water), string (thread), water.

Work progress

1. Measure the length, width and height of the rectangular parallelepiped with a tape measure!

2. Record the results in table 1!

3. The measurement is repeated two more times!

4. Pour enough water into the measuring cylinder to completely submerge the parallelepipeds and determine the initial volume of water V0.

5. Record results in Table 2!

6. Wrap it in a string and completely immerse it in water, determining the water volume V1.

7. Record the results in table 2!

8. The measurement is repeated two more times!

9. Calculate the average value of the measurements!

10. Record the results in the appropriate table!

11. Calculate the volume of the parallelepiped!

12. Record the results in the appropriate table!

13. Calculate the relative error and absolute error of the volume.

Registration and processing of obtained data

Table 1

Linear dimensions and volume of bodies, measured with a tape measure

Body	Length a a, mm,	Width b b, mm,	Height c c, mm	Volume V, mm3	Volume, V V mm3	r, %
rectangular parallelepiped
Average value

2. tabula

Body volume using the immersion method

Body	Water volume V0 V0 cm3	Total volume V1 V1, cm3	Body volume V, cm3	Volume V V, cm3	r, %
rectangular parallelepiped
Average value

Write one calculation example using the given formulas and indicate which measurement it is given for!

Calculation example:

Calculates the average value of a physical quantity, for example a vid = (a1+ a2+ a3)/3 =

Calculate the volume of the parallelepiped V= abc=

Calculate the volume of the immersed parallelepiped V =V -Vo =

Length relative error r= a /avid 100% =

Volume relative error rV=ra+ rb+rc =

Volume absolute error V = rV V/100=

Analysis, evaluation and conclusions of the results

What is the absolute error when sizing using

a) tape measure;

b) measuring cylinder?

2. With which measuring instrument is it possible to make more accurate measurements?

3. Compare the accuracy of the obtained volume values in different measurements for the body?

4. Compare the accuracy of the obtained volume values in direct and indirect measurements!

Research laboratory work in physics

Evaluation criteria

Task	Criteria	Points
Determine the sizes correctly	length	3
width
height
Define correctly	Water volume	3
Total volume
Body volume
Calculation	volume	5
volume of the immersed parallelepiped
volume relative error
the absolute error of the volume
average value of a physical quantity
Average value of length, width and height
Analysis of results	Analyzes the obtained data logically and reasonably, compared to the sources of information.	4
Evaluate the weaknesses and limitations of the experiment.
Conclusions are precisely formulated according to the obtained results.