# Exercises to read tables and charts properly: First set

Published on 01.24.2023

Middle School
Life and earth sciences

Newspaper and magazine articles, energy studies and technical documents on various types of equipment all often include charts and tables. These have become more diverse with the rise of digital technology. To learn effectively, it’s important to be able to read these diagrams. With this first in a series of exercises, ranging from very easy to much more challenging, Planète Energies is helping you do just that.

## Exercise level 1 / beginner:

This exercise shows how the output of a wind turbine rises and falls.

Reading Simple Line Charts: The Example of a Wind Turbine

A wind turbine will not turn when wind speeds are low, i.e., below 3 m/s or around 10 km/h, or else it is disconnected from the grid owing to its overly irregular output. The stronger the wind blows, the more the turbine generates. But the increase in output does not continue indefinitely, as wind turbines have limits depending on their size and technology.

Take the example of a 0.75 MW wind turbine. Models like this have a mast that is around 75 meters high and a blade span diameter of 40 meters. When the wind speed exceeds approximately 50 km/h, the power generated by the turbine levels out. At dangerous wind speeds of around 90 km/h or more, the turbine is stopped for safety reasons and power output drops immediately to zero.

At what wind speed does a wind turbine reach half its maximum output? 1) 7.5m/s 2) 8.5 m/s 3) 9 m/s

At 9 m/s or around 32 km/h. However, the chart gives just a rough overview. The actual Answer: s position in figures vary according to atmospheric pressure, temperature and the wind turbine’ relation to the wind