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 conversion factor . So, radians.Now, we can substitute the value of into the lift coefficient equation: Therefore, the lift coefficient is .(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.Given that the chord length is 1.5 m, the wing span is 2 m, and the airspeed is 30 m/s, we can calculate the wing area as: Now, we can substitute the values of , , , and into the lift equation: Therefore, the lift force is .