Work procedure and data processing. 1.Take balls (3 – 5). Find the values of balls and liquid densities in the density table

1.Take balls (3 – 5). Find the values of balls and liquid densities in the density table. Materials, the balls and the liquid are made of, are given by the teacher. Enter the results into table 1.

2. Measure the radius of the ball by means of a microscope. Place the microscope on a white sheet of paper opposite sun light. Get a clear picture of a scale’s net by turning a limb of the microscope top lens to and fro. Get a clear picture of the ball by turning a limb of the microscope bottom lens to and fro. Count the number of pitches N on the scale’s net corresponding to the diameter of the small-shot ball. Scale factor a is written on the microscope body so it is possible to calculate the radius of the ball by the formula:

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Repeat measurements 3 times turning the ball concerning to the scale. Calculate arithmetic mean of three radii. Enter the results into table 1.

3. Measure the distance between the upper and the lower scores L by a ruler.

4. Find the values of the ball and the liquid densities in the density table. Materials, the ball and the liquid are made of, are given by the teacher.

5. Enter the results into table 5.1.

6. Calculate the internal friction coefficient for each ball by the formula (7).

7. Carry out data processing.

8. Calculate average value of the internal friction coefficient. Calculate deviation from average value Δη_i

9.Calculate the root-mean-square error of the arithmetic mean .

10. Multiply by the Student’s coefficient t_st for the amount of experiments n and reliable probably = 0,95 (for n= 3 t_st = 4,30; for n= 4 t_st = 3,18; for n= 5 t_st = 2,78).

11.Write down the obtained result according to the formula:

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questions to be admitted for doing laboratory work and its defence

1. Enumerate the transport transport phenomena. What quantity is transferred during each of them?

2. Explain the cause of internal friction.

3. Explain the cause of heat conductivity.

4. Explain the cause of diffusion.

5. Write and explain Newton’s law for a steady laminar stream.

6. How does the coefficient of internal friction depend on temperature?

7. What is physical sense of velocity gradient?

8. Describe the Stock’s method for the coefficient of internal friction determination.

9. What forces make the ball move in liquid?

10. Deduce the formula for calculation the coefficient in our experiment.

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