Question 4 (10+10=20 Point): A symmetric airfoil operates at a small angle of attack (alpha =2^circ ) in subsonic flow. The lift coefficient is given by C_(L)=2pi alpha (with alpha in radians). (a) Calculate the lift coefficient (C_(L)) (b) If the chord length is 1.5 m.wing span is 2 m and the airspeed is 30m/s,rho _(infty )=1.225kg/m^3 determine the lift force.

(a) To calculate the lift coefficient , we need to convert the angle of attack from degrees to radians. We know that radians. So, radians.Now, we can substitute the value of into the lift coefficient formula: Therefore, the lift coefficient is approximately 0.21.(b) To determine the lift force, we can use the lift equation: where is the lift force, is the air density, is the airspeed, is the wing area, and is the lift coefficient.First, let's calculate the wing area . Since the airfoil is symmetric and the chord length is 1.5 m, the wing span is 2 m, we can assume the wing area is a rectangle: Now, we can substitute the values into the lift equation: Therefore, the lift force is approximately 34.29 N.