A company is testing a carbon-fibre wing that can serve either as an aircraft wing in…
PHYSICS · Multi-part · CBSE · Physics · Mechanical Properties of Fluids · Mechanical Properties of Fluids
Problem
A company is testing a carbon-fibre wing that can serve either as an aircraft wing in air or as a hydrofoil in water. The wing area is 22m2 and the total mass it must support is 600kg. For air, take the density as 1.2kgm−3; for water, take 1000kgm−3. Assume g=9.8ms−2.
(i) Determine the upward force the wing must produce to keep the supported mass in equilibrium.
(ii) In a wind-tunnel test, air is made to flow at 32ms−1 over the wing’s upper surface while the flow speed just below the wing is 10ms−1. Show whether these speeds are sufficient to supply the force calculated in part (i).
(iii) When the same wing is used as a hydrofoil, the speed of water past the lower surface is 5ms−1. Calculate the minimum speed of water over the upper surface required to generate the force found in part (i).
(iv) Comment on the relative practicality of achieving the speed found in part (iii) compared with the wind-tunnel speeds in part (ii).