Anemometer is blowing on the back of the cup on the opposite end of the cross. Since a hollow hemisphere has a drag coefficient of .38 on the spherical side and 1.42 on the hollow side, more force is generated on the cup that is presenting its hollow side to the wind. Because of this asymmetrical force, torque is generated on the axis of the anemometer, causing it to spin. Theoretically, the speed of rotation of the anemometer should be proportional to the wind speed, because the force produced on an object is proportional to the speed of the fluid flowing
Does exactly what it says on the tin Does exactly what it says on the tin "It does exactly what it says on the tin" was originally an advertising slogan in the United Kingdom, which then became a common idiomatic phrase. It colloquially means that the name of something is an accurate description of its qualities. It is akin to the previously existing phrases "by name and by nature" and "it lives up to its name". It originated in a series of television advertisements by the woodstain and wood-dye manufacturer Ronseal, initiated in 1994 and still being broadcast . The slogan was created by Liz Whiston and Dave