A jet of water 75 mm in diameter having velocity of 20 m/s strikes 9 series of flat plates arranged around the periphery of a wheel such that each plate appears successively before the jet. if the plates are moving at a velocity of 5 m/s , compute the force exerted by the jet on the plate , the work done per second on the plates and efficiency of the jet
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The work done on the jet plates is 4972.5 N.m
Explanation:
Given data:
- Diameter of jet = 75 mm
- velocity of water = 20 m/s
- Velocity of plates = 5 m/s
Solution:
Area of jet:
a = π / 4 (75 / 1000)^2
a = 0.0442 m^2
The normal thrust on a moving flat plate on the plate
F = w a ( v − u)^2 g
F = 9810 × (0.00442)(20 − 5)^2 / 9.81 = 994.5 N
Work done per second by the jet on the plate
= F×u
= (994.5 × 5) = 4972.5 N.m
Hence the work done on the jet plates is 4972.5 N.m
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