7. Nellie and Goldie are coasting on their bicycles down a 10° slope at 15 m/s through still air. The mass of Nellie and her bicycle is 60 kg. The mass of Goldie and her bicycle is 90 kg. The cross-sectional area of Nellie and her bicycle is 0.45, while the crosssectional area of Goldie and her bicycle is 0.60. The drag coefficient for both cyclists is 0.70. Other than gravity and air resistance, the external forces acting on the two bicycle and rider systems are the same. Which cyclist is more affected by air resistance?

1. As part of your role at a heavy-goods vehicle manufacturer, you have been asked to determine the drag caused by the boundary layer developing along a section of the trailer roof, which can be treated as having constant pressure, as the truck travels at 10 m/s. The velocity profile in this region is given by: - A (+ 1) + 1 us where us is the velocity at the edge of the boundary layer. A and B are constants.

Air at 20°C flows at V = 80.0 m/s over a smooth flat plate of length L = 17.5 m. Plot the turbulent boundary layer profile in physical variables (u as a function of y) at x = L. Compare the profile generated by the one-seventh-power law, the log law, and Spalding’s law of the wall, assuming that the boundary layer is fully turbulent from the beginning of the plate.

Compute the lift and drag coefficients for a symmetric, diamond-shaped airfoil with a thickness-to-chord ratio t/c equal to 0.10, flying at Mach 3.5 in air (y=1.4) at zero angle of attack. M₂ - 3.5

Q1

An aeroplane has a rectangular planform wing with a span of 12 m and a chord of 2 m. The aircraft is flying at cruising speed of 62 m/s at an altitude of 3,200 m. Assume that the skin-friction drag on the wing can be approximated by the drag on a flat plate of the same dimensions at 0° incidence. Calculate the skin-friction drag and the maximum boundary layer thickness assuming (i) a completely laminar flow, and (ii) a completely turbulent flow. Assume μ = 1.63.10-5 N s/m², p = 0.89 kg/m³. Then, calculate the skin-friction drag accounting for transition at Recr= 5.105. What would the drag benefit be if transition was delayed to a Reynolds number of 106? What reduction in a propeller engine power would this imply in the cruise condition, assuming a propeller efficiency of 0.88?

Required information A disk-gap-band parachute has a drag of 1600 lbf when tested at 15 mi/h in air at 20°C and 1 atm. The diameter of the parachute is 43 ft. For air at 20°C and 1 atm, take p≈ 1.20 kg/m³. Take π = (22/7). If the drag on Mars is 65,000 lbf and the velocity is 1300 mi/h in the thin Mars atmosphere and p≈ 0.020 kg/m³, what is the drag coefficient on Mars? The drag coefficient is

and power for part b