Drava water speed Drava water speed assessmentassessment

The goalThe goal

• To assess the water flow speed of the river To assess the water flow speed of the river DravaDrava

• To assess the average speed valueTo assess the average speed value

• To calculate the maximum absolute errorTo calculate the maximum absolute error

• To calculate the maximum relative errorTo calculate the maximum relative error

• Most importantly: connecting and getting Most importantly: connecting and getting to know new friends and culturesto know new friends and cultures

A Description of the A Description of the measuringmeasuring• Utensils: a ferry, a stopwatch, Utensils: a ferry, a stopwatch,

measuring tape, pieces of papermeasuring tape, pieces of paper• Instructions:Instructions:

Step oneStep one: : Board the ferry and Board the ferry and measure it’s width.measure it’s width.

A Description of the A Description of the measuringmeasuring

• Step two: Once the width of the ferry Step two: Once the width of the ferry is measured, throw a piece of paper is measured, throw a piece of paper into the water at one end of the into the water at one end of the ferry.At the same moment, start the ferry.At the same moment, start the stopwatch and measure the time stopwatch and measure the time needed for the paper to reach the needed for the paper to reach the other end of the ferry. other end of the ferry.

A Description of the A Description of the measuringmeasuring

• Step three: It is possible to get the Step three: It is possible to get the speed of the river flow from the data speed of the river flow from the data (the width of the ferry and the time (the width of the ferry and the time needed for the paper to reach the needed for the paper to reach the other end of it).other end of it).

Measuring resultsMeasuring results

MEASURING l (m) t /s) v (m/s) ∆v(m/s)

1. 7.98 6.03 1.32 0.01

2. 8.03 6.27 1.28 0.033. 8.01 6.25 1.28 0.03

4. 8.02 5.98 1.34 0.03

5. 7.97 6.06 1.31 0.00

6. 8.01 5.96 1.34 0.037. 8.03 6.17 1.30 0.018. 7.97 6.00 1.33 0.02

9. 8.00 6.19 1.29 0.02

10. 8.04 6.06 1.33 0.02

11. 8.02 6.15 1.30 0.01

12. 7.99 6.05 1.32 0.01

13. 8.02 6.13 1.30 0.01

14. 7.97 6.01 1.33 0.02

Average value / / 1.31 /

The average value can be calculated with the following relation:

The maximum absolute error with the following relation:

And the maximum relative error with the following relation:

The conclusionThe conclusion

• We measured the surface speed of the river We measured the surface speed of the river Drava’s flowDrava’s flow

• The current speed was 1,31 m/s or 4,72 km/hThe current speed was 1,31 m/s or 4,72 km/h

• The average speed on the location Brodić is 7 The average speed on the location Brodić is 7 km/h or 1,90 m/skm/h or 1,90 m/s

• The water level is currently high and The water level is currently high and therefore the speed will be slower therefore the speed will be slower

• The biggest absolute - 0,02 m/sThe biggest absolute - 0,02 m/s

• The biggest relative error -1,5%The biggest relative error -1,5%

Drava water speed Drava water speed assessmentassessment