479 Horizontal Motion: The horizontal component of velocity ... - Wuala

91962_05_R1_p0479-0512 6/5/09 3:54 PM Page 497
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R1–25. The bottle rests at a distance of 3 ft from the center
of the horizontal platform. If the coefficient of static friction
between the bottle and the platform is m s = 0.3, determine
the maximum speed that the bottle can attain before
slipping. Assume the angular motion of the platform is
slowly increasing.
3 ft
©F b = 0; N - W = 0 N = W
Since the bottle is on the verge of slipping, then F f = m s N = 0.3W.
©F n = ma n ; 0.3W = a W
32.2 bay2 3 b
y = 5.38 ft>s
Ans.
R1–26. Work Prob. R1–25 assuming that the platform
starts rotating from rest so that the speed of the bottle is
increased at 2 ft>s 2 .
3 ft
Applying Eq. 13–8, we have
©F b = 0; N - W = 0 N = W
Since the bottle is on the verge of slipping, then F f = m s N = 0.3W.
©F t = ma t ; 0.3W sin u = a W
32.2 b(2)
©F n = ma n ; 0.3W cos u = a W
32.2 bay2 3 b
[1]
[2]
Solving Eqs. [1] and [2] yields
y = 5.32 ft>s
Ans.
u = 11.95°
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