(a) Set up equations of motion for the position u(t) of the main mass and the
position z(t) of the oscillator mass, assuming that the main mass never loses
contact with the plane.
(b) Explain why the speed _
u of M could have a non-zero average, so that the main
mass moves in one direction along the plane, on the average.
(c) Derive an expression for the average speed of the main mass, and discuss its
dependency of the frequency of excitation X and the oscillator orientation a.
Fig. P7.7
7.9 Problems
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