College Physics Problem 2.6

A helicopter blade spins at exactly 100 revolutions per minute. Its tip is 5.00 m from the center of rotation.
(a) Calculate the average speed of the blade tip in the helicopter’s frame of reference.
(b) What is its average velocity over one revolution?

SOLUTION:

a) The average speed of the blade tip is equal to the distance traveled divided by the time elapsed.

speed= frac{distance traveled}{time elapsed}

speed= frac{2 pi r}{t}

speed= frac{2 pi (5.00 m)}{60 s}times 100 rev=52.36 m/s

b) After one revolution, the tip of the blade is at the same position at it is originally. This means that the displacement is zero. Thus, the velocity is zero.

v=0 m/s

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