Question

A kite is a very simple wing that experiences lift and drag as the wind blows past it and is held in place by the string. A kite has a mass of 9g, a coefficient of lift of 1.25, and a surface area of 2 m 2 . In a 24 km/h wind the kite sits at an angle so that is has a cross-sectional area of 1 m2 . (a) Draw a free body diagram for the kite. (1 point) (b) Calculate the x and y components of tension in the string if the kite is in static equilibrium. (3 points) (c) Express the tension in angle and magnitude representation. (2 points)

Answer 1

The angle at which the kite sits in the wind is given by Cross-sectional area of the kite when the wind is blowing/Cross-sectional in still area=1/2.

The net vertical force acting on the kite F_v=Drag force due to the wind-weight of kite= where b is the coefficient of lift and v is the velocity of wind.

Now v=24 km/h=24*1000/60 m/s=400 m/s.

b=1.25.

Weight of kite=

Therefore we have,

Therefore the horizontal force acting on the kite is such that

Therefore

Thus tension in the string is

The tension is directed at an angle