Question

The higher the altitude the more slowly windmills rotate at the same wind speed. Which one of the following is the best reason why the blades of windmills rotate More slowly in higher places at the same wind speed? 1. *

1 point

(a) The air is less dense as altitude increases.

(b) The temperature is lower as altitude increases.

(c) Gravity becomes less as altitude increases.

(d) It rains more often as altitude increases.

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Answer 1

The correct answer is (a) the air is less dense as the altitude increases.

• At higher altitudes, it rains more often.
• As we go up, the pressure gradient between the warm air cold air increases with height and the air flows much faster, therefore air does not affect the speed of windmills.
• The rainfall restricts the windmills to rotate and therefore slows them down.
• All the other options do not affect i.e. gravity and temperature do not affect the speed of the windfall.