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 a 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. Given that the angle of attack is , we can convert it to radians using the formula: Substituting the given value of , we get: Now, we can calculate the lift coefficient using the given formula: Substituting the value of , we get: 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- is the lift coefficientGiven that the chord length is 1.5 m, wing span is 2 m, and the airspeed is 30 m/s, we can calculate the wing area as: Substituting the given values, we get: Now, we can calculate the lift force using the lift equation: Therefore, the lift force is approximately 0.98 N.