Consider a solid iron sphere entering the earth's atmosphere at 13 km/s (slightly above es- cape velocity) and at an angle of 15° below the local horizontal. The sphere diameter is 1 m. The drag coefficient for a sphere at hypersonic speeds is approximately 1. The den- sity of iron is 6963 kg/m³. Calculate (a) the altitude at which maximum deceleration oc- curs, (b) the value of the maximum deceleration, and (c) the velocity at which the sphere would impact the earth's surface.

Air at 20°C, 1 atm flows with a velocity of 4.5 m/s over a flat plate having a sharp leading edge. The plate surface isothermal at 60°C. (a), determine the following parameters at a distance of 1.89m. i)Mass entrainment in the boundary layer (ii)The skin friction coefficient

Determine the lift coefficient of a supersonic aerofoil, approximated by a flat plate. It is flying at Ma 3.4 at an angle of attack of 7°. Assume the fluid to be air as a perfect gas with k=1.4.

6. For a wing of aspect ratio AR, having an elliptical lift distribution, the induced drag coefficient is (where CL is the lift coefficient) (b) TAR CL 2TAR (d) TAR2 (a) TAR 7. Laminar flow airfoil is used to reduce the (a) pressure drag (b) induced drag (c) skin friction drag (d) wave drag 8. Set the aerofoil your chosen angle of incidence is gives a good installed pressure distribution. (a) twelve degree (b) ten degree (c) eight degree 9. The critical Mach number for a thick airfoil will be (a) lesser than a thin airfoil. (b) greater than a thin airfoil. (c) equal to a thin airfoil. (d) cannot be related to thin airfoil 10. What is the dimension for Lift coefficient? (a) N/s (b) kg/N (c) Dimensionless