A small button placed on a horizontal rotating platform with diameter 0.328 will
ID: 2205922 • Letter: A
Question
A small button placed on a horizontal rotating platform with diameter 0.328 will revolve with the platform when it is brought up to a rotational speed of 37.0 , provided the button is a distance no more than 0.143 from the axis.A) What is the coefficient of static friction between the button and the platform?
Take the free fall acceleration to be = 9.80 .
B) How far from the axis can the button be placed, without slipping, if the platform rotates at 62.0 ?
Take the free fall acceleration to be = 9.80 .
Explanation / Answer
at r = 0.143m v = 2 x 3.14 x 0.143 x 37/60 = 0.55m/s coefficient friction µ = Fc / Fn = ma/mg = a/g a = v^2/r = 0.55^2/0.143 = 2.11m/s^2 µ = 2.11 / 9.8 = 0.21 b) at 62rpm, v = 2 x 3.14 x r x 62/60 = 6.48r for no slipping the acceleration must remain at 2.11m/s^2 a = v^2/r 2.11 = (6.48r)^2 / r 2.11 = 41.99r r = 0.050m