Project ForgeAir discharges steadily through a horizontal nozzle and impinges on a stationary vertical plate. The inlet and outlet areas of the nozzle are 0.1 m² and 0.02 m², respectively. Take air density as constant and equal to 1.2 kg/m³. If the inlet gauge pressure of air is 0.36 kPa, the gauge pressure at point O on the plate (the stagnation point directly facing the nozzle) is __________ kPa (round off to two decimal places).
Explanation
Continuity: V1×0.1=V2×0.02 → V2=5V1. Bernoulli (inlet to nozzle exit, exit gauge pressure=0): 360+0.5×1.2×V1² = 0.5×1.2×(5V1)² → 360+0.6V1²=15V1² → V1²=25 → V1=5 m/s, V2=25 m/s. Bernoulli (nozzle exit to stagnation point O, V=0): p_O = 0.5×1.2×25² = 375 Pa ≈ 0.38 kPa.
Source: GATE ME 2020 Session 1 (ME-1) (2020)
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