A model of a helicopter rotor has four blades, each 3.40 m long f...

Question

A model of a helicopter rotor has four blades, each 3.40 m long from the central shaft to the blade tip. The model is rotated in a wind tunnel at 550 rev/min. (a) What is the linear speed of the blade tip, in m/s?

Accepted Answer

Welcome back everybody. We have a wind turbine. So let me go ahead and try all our wind wind here and with any good wind turbine we have the blades jutting out of it. Now, we are told that any given one of these blades as a length of 120 ft, meaning the circle that this propeller makes has a radius of 100 and 20 ft. Were also told that it rotates with an R. P. M. Of 10. We are asked to find what the linear speed is at the blade tips. Well, our linear speed or tangential velocity is going to be equal to the radius, times our angular velocity given by omega. So we actually need to convert this value into our omega because our omega is given in radiance per minute. We are given 10 revolutions. Sorry here revolutions or one minute. So let me go ahead and multiply this by two high radiance Over one revolution since we know there are two pi radiance in one revolution. These units cancel out, and we are given that are angular velocity is 20 high radiance or in it. Great! Now that we have this value, we can go ahead and plug it into our above formula to find our tangential velocity Are tangential velocity is equal to our radius of 120 ft. Times Or angular velocity of 20 i. And when you plug this into our calculator, get that our tangential velocity is 7540 ft per minute corresponding to our final answer choice of B. Thank you guys so much for watching Hope this video helped. We will see you all in the next one.

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