Question

A helicopter propeller blade starts from rest and experiences a constant angular acceleration of 14.0 rad/s2. Find the speed of a point on the blade 5.60 m from the axis of rotation when the blade has completed 13 revolutions.

Answer 1

Using equation of rotational motion (iii), we have

² = _i² + 2

where, _i = initial angular speed of blade = 0 rad/s

= constant angular acceleration = 14 rad/s²

= angular distance completed by blade = 13 rev = 81.6 rad

then, we get

² = (2) (14 rad/s²) (81.6 rad)

= 2284.8 rad²/s²

= 47.8 rad/s

Therefore, the speed of a point on the blade from the axis of rotation which will be given by -

v = r

v = [(5.60 m) (47.8 rad/s)]

v = 267.6 m/s