Explanation Given information: The width of the car W = 74.4 in . The height of the car H = 57.4 in . The drag coefficient of the car C d = 0.4 . The range of air speed is 15 m / s < V < 35 m / s . The range of change the air density is 1.11 kg / m 3 < V < 1.29 kg / m 3 . The frontal area A = 0.85 × W × H of the rectangle that outlines the front of a car. The air density range corresponds to the temperature 0 ° to 45 ° . The drag coefficient is C d = F d 1 2 ρ V 2 A (1) The power requirement to overcome air resistance is P = F d V (2) Calculation: Calculate the frontal area of the car ( A ) using the relation as shown below. A = 0.85 × W × H Substitute 74.4 in . for W and 57.4 in . for H . A = 0.85 × 74.4 × 57.4 = 3 , 629.976 in . 2 × ( 0.0254 m 1 in . ) 2 = 2.342 m 2 Calculate the drag force acting on the car using Equation (1) as shown below. F d = C d × 1 2 ρ V 2 A = 1 2 C d ρ V 2 A Substitute 0.4 for C d and 2.342 m 2 for A . F d = 1 2 × 0.4 × ρ V 2 × 2.342 = 0.4684 ρ V 2 Calculate the power requirement to overcome the air resistance for a car using Equation (2) as shown below. Substitute 0.4684 ρ V 2 for F d in Equation (2). P = 0.4684 ρ V 2 × V = 0.4684 ρ V 3 (3) Provide the air density-temperature relationship as shown in Table below. Temperature ( ° C ) 0 5 10 15 20 25 30 35 40 45 Air density ρ , ( kg / m 3 ) 1