1. Drava water speed assessment

2. The goal To assess the water flow speed of the river Drava To assess the water flow speed of the river Drava To assess the average speed value To assess the average speed value To calculate the maximum absolute error To calculate the maximum absolute error To calculate the maximum relative error To calculate the maximum relative error Most importantly: connecting and getting to know new friends and cultures Most importantly: connecting and getting to know new friends and cultures

3. A Description of the measuring Utensils: a ferry, a stopwatch, measuring tape, pieces of paper Utensils: a ferry, a stopwatch, measuring tape, pieces of paper Instructions: Instructions: Step one : Board the ferry and measure it’s width. Step one : Board the ferry and measure it’s width.

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

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

6. Measuring results MEASURINGl (m)t /s)v (m/s)∆v(m/s) 1.7.986.031.320.01 2.8.036.271.280.03 3.8.016.251.280.03 4.8.025.981.340.03 5.7.976.061.310.00 6.8.015.961.340.03 7.8.036.171.300.01 8.7.976.001.330.02 9.8.006.191.290.02 10.8.046.061.330.02 11.8.026.151.300.01 12.7.996.051.320.01 13.8.026.131.300.01 14.7.976.011.330.02 Average value // 1.31 /

7. 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:

8. The conclusion We measured the surface speed of the river Drava’s flow We measured the surface speed of the river Drava’s flow The current speed was 1,31 m/s or 4,72 km/h The current speed was 1,31 m/s or 4,72 km/h The average speed on the location Brodić is 7 km/h or 1,90 m/s The average speed on the location Brodić is 7 km/h or 1,90 m/s The water level is currently high and therefore the speed will be slower The water level is currently high and therefore the speed will be slower The biggest absolute - 0,02 m/s The biggest absolute - 0,02 m/s The biggest relative error -1,5% The biggest relative error -1,5%

9. Drava water speed assessment