A Verdant Power water turbine (a \"windmill\" in water) turns in the East River
ID: 1460890 • Letter: A
Question
A Verdant Power water turbine (a "windmill" in water) turns in the East River near New York City. Its propeller is 2.5 m in radius and spins at 32 rpm when in water that is moving at 2.0 m/s. The rotational inertia of the propeller is approximately 3.0 kgm2. Part A Determine the kinetic energy of the turbine in joules. Express your answer using two significant figures.Determine the electric energy in joules that it could provide in 1 day if it is 100% efficient at converting its kinetic energy into electric energy. Assume that the energy delivered per revolution is equal to the rotational kinetic energy of the turbine. Express your answer using two significant figures.
Explanation / Answer
w = 32 rpm = 32*2*pi/60 rad/s
= 3.351 rad/s
Rotational kinetic energy = 0.5*I*w^2
= 0.5*3*(3.351)^2
= 16.84 J
This is the kinetic energy they are talking about
Answer: 17 J (in 2 significant figure)
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In 1 s , energy provided = 16.84 J
time in 1 year = 24*3600 s = 86400 s
Total energy provided in 1 day = 16.84 * 86400
=1.5*10^6 J
Answer: 1.5*10^6 J
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