An airplane propeller is 2.78{m} in length (from tip to tip) and has a mass of 1

Question

An airplane propeller is 2.78{m} in length (from tip to tip) and has a mass of 117{kg} . When the airplane's engine is first started, it applies a constant torque of 1970{N*m} to the propeller, which starts from rest. Part A What is the angular acceleration of the propeller? Treat the propeller as a slender rod. Part B What is the propeller's angular speed after making 5.00{rev} ? Part C How much work is done by the engine during the first 5.00{rev} ? Part D What is the average power output of the engine during the first 5.00{rev} ? Part E What is the instantaneous power output of the motor at the instant that the propeller has turned through 5.00{rev} ?

Explanation / Answer

rotational kinetic energy = 1/2 x I x angular velocity^2 I = moment of inertia sooooo.... diameter = 2.15 mass = 98 moment of inertia of a rod = m x L^2/12 98 x 2.15^2 = 37.75 = moment of inertia angular velocity = 2600 x 2pi / 60 = 104.7 rads-1 0.5 x 37.75 x 104.7^2 = 206 909J hope this makes sense.... and helps. for B. go back and reduce the mass by 75% i think it should come up to something around 11000rpm.

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