Because of their knowledge of physics and interest in transportation, you\'ve go
ID: 1509451 • Letter: B
Question
Because of their knowledge of physics and interest in transportation, you've got a summer job in the US company Sikorsky, they are interested in investigating the energy consumption of its new helicopter three rotors (Sikorky S-97 Raider). The rotor blade may be regarded as a thin rod. If each of the three rotor blades of the helicopter measures 3.75 m long and has a mass of 135 kg. a) Determine the energy needed to put to work the rotors (2) until the blades reach a speed of 5.0 rev / s. b) If regular gasoline was used to produce that energy -How gallons of it would be needed? Compare that with the energy consumed by an average household in Puerto Rico in a month. Explain your answers.
Explanation / Answer
Here,
mass , m = 135 Kg
L = 3.75 m
angular speed , w = 5 rev/s
w = 31.41 rad/s
Energy needed for rotors = 0.5 * 3 * (m * L^2/3) * w^2
Energy needed for rotors = 135 * 3.75^2 * 0.5 * 31.41^2
Energy needed for rotors = 9.37 *10^5 J
the Energy needed for rotors is 9.37 *10^5 J
---------------------------------------------------
b)
calorific value of gasoline , S = 47300 * 10^3 J/Kg
let the mass of gasoline is m
9.37 *10^5 = m * 47300 * 10^3
m = 0.0198 Kg
volume = 0.0198/719.7 m^3
volume = 2.751 *10^-5 m^3
volume = (2.751 *10^-5 * 264.17) gallon
volume = 0.00727 gallon
the voluem of gasoline consumed is 0.00727 gallon