426. A 20-1lb block B is suspended from a 5-ft cord attached to a 50-lb cart A hich can move freely down the incline. Determine for the instant the system is peleased from rest (a) the acceleration of the cart, (b) the acceleration of the block, 50 lb (c) the tension in the cord. 12 7* A car climbs the hill AB at a constant speed as shown. If the driver does not change the throttle setting or shift gears, determine the magnitude of the acceleration of the car immediately after entering (a) the level section BC, (b) the downhill sec- 20 lb tion CD.

Question B3 The engine of an aeroplane is equipped with an ideal convergent nozzle with an area ratio Ainlet 2.035 ( -A-2.035), as in Figure Q-B3. The aeroplane is flying at an altitude of 11 Aexit km where the atmospheric pressure and temperature are 0.23 bar and 216K respectively. You may assume the combustion gases entering the nozzle have the same property as air (i.e. y=1.40, R=287 J/kgK and Cp-1004.5J/kgK). Page 6 Question B3 continued inlet exit Amles/Aexit -AVAJ-2.035 Figure Q-B3 a) If the nozzle operates at its critical condition, calculate: the inlet Mach number M;. nozzle's exit velocity V, the inlet stagnation pressure Por- the inlet static pressure FG The stagnation Aj P, and the nozzle's gross thrust per unit exit area temperature of the gases entering the nozzle is To 1200 K. b) If the stagnation pressure at the inlet of the nozzle is reduced to 80% of its value in part (a), determine the exit static temperature 7;, the nozzle's gross thrust per unit exit area FG. The…