A uniform sphere of radius a rests against a verticall wall supported by a string of length 2a fixed to a point of its surface and to a point of the wall.
If the wall is rough and the sphere is on the point of sliding down the wall when the string is inclined at 30 degree to the vertical, find the coefficient of friction between the sphere and the wall.
Answer: 1
AL app math。Statics & Friction
2009-03-04 6:07 am
回答 (1)
2009-03-04 6:21 am
✔ 最佳答案
Please look the following figure:http://i726.photobucket.com/albums/ww265/physicsworld2010/physicsworld03Mar032216.jpg
For the system is in limiting equilibrium, F = uR, where u is the coefficient of friction.
Horizontal: Tsin30* = R, T = 2R ... (1)
Since the string makes an angle 30* with the vertical wall.
So, 2asin30* = a = radius of the sphere
So, B is the toppest point of the sphere.
Take moment about O
aF = aTsin30*
uR = 2R / 2
Coefficient of friction, u = 1
參考: Physics king
收錄日期: 2021-04-19 13:43:30
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