The helicopter in the drawing is moving horizontally to the right at a constant velocity. the weight of the helicopter is w=50900 n. the lift force l generated by the rotating blade makes an angle of 21.0° with respect to the vertical.
(a) what is the magnitude of the lift force?
(b) determine the magnitude of the air resistance r that opposes the motion.

Two kilograms of air within a piston–cylinder assembly executes a carnot power cycle with maximum and minimum temperatures of 800 k and 300 k, respectively. the heat transfer to the air during the isothermal expansion is 60 kj. at the end of the isothermal expansion the volume is 0.4 m3. assume the ideal gas model for the air. determine the thermal efficiency, the volume at the beginning of the isothermal expansion, in m3, and the work during the adiabatic expansion, in kj.