HW_4_Solution

HW_4_Solution - W 7 745 hp 1 W 20 W 3 The work needed to...

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Solution of Homework Assignment 4 1. Then the total mechanical energy of the river water per unit mass becomes ( a ) kJ/k 0.994 2 2 2 2 2 mech /s m 1000 kJ/kg 1 2 ) m/s 5 ( m) 100 )( m/s (9.81 2 V gh ke pe e The power generation potential of the river water is obtained by multiplying the total mechanical energy by the mass flow rate, ( b ) kg/s 200,000 /s) m 00 )(2 kg/m 1000 ( 3 3 V m MW 1 8 . 98 kW 800 , 198 kJ/kg) 4 kg/s)(0.99 000 , 200 ( mech mech max e m E W 2. The power produced by a model aircraft engine is to be expressed in different units. Analysis Using appropriate conversion factors, we obtain ( a ) ft/s lbf 1 76 . 4 Btu/s 1 ft/s lbf 169 . 778 W 056 . 1055 Btu/s 1 ) W 20 ( W ( b ) hp 0.0268
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Unformatted text preview: W 7 . 745 hp 1 ) W 20 ( W 3. The work needed to accelerate a body is simply the change in the kinetic energy of the body, kJ s m kg kJ s m kg V V m W a 9 . 246 ) / 1000 / 1 ]( ) 3600 80000 )[( 1000 ( 2 1 ) ( 2 1 2 2 2 2 2 1 2 2 4. 5. The mechanical energy is the form of energy that can be converted to mechanical work completely and directly by a mechanical device such as a propeller . It differs from thermal energy in that thermal energy cannot be converted to work directly and completely. The forms of mechanical energy of a fluid stream are kinetic, potential, and flow energies....
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HW_4_Solution - W 7 745 hp 1 W 20 W 3 The work needed to...

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