In a test experiment on a model aeroplane in wind tunnel, the flow speeds on the upper and lower surfaces of the wings are \( 70 \, \text{m s}^{-1} \) and \( 65 \, \text{m s}^{-1} \) respectively. If the wing area is \( 2 \, \text{m}^2 \), the lift of the wing is __________ N.
(Given density of air \( = 1.2 \, \text{kg m}^{-3} \))
