11it is in the direction of the applied force....
DETERMINE THE DIRECTION OF FRICTION FOR PURE ROLLING MOTION OF THE RING:
Please give reason.
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UP 0 DOWN 0 0 7
7 Answers
1FROM ANOTHER VIEW POINT :
FOR THIS F WHICH PRODUCES A TORQUE, ω becomes greater than v . To REDUCE THIS ω an anti-torque needs to be given which is given by the friction in the forward direction.
This direction of friction also increases v as it's in the same direction.
This is the condition for pure rolling.
29just asume that the friction is in forward direction...and the make equation
F + f = Ma..where f is frictional force..and (F - f)R = MR2α
so from here f comes to be zero..but this is only valid in case of ring..in other cases frictional force wont be 0
11ya to finish off....with hep from govind
F + f = Ma........(1)
clockwise torque due to Force F..... = FR
anti-clockwise torque due to friction.. = fR
so net clock wise torque =FR - fR = (F - f)R
net torque = I @ (@ = alpha)
( F - f ) R = M R2 @...(2)
solving 1 & 2....
Ma - 2f = M R @
for pure rolling....
a = R @
so f = 0
1AN ADDITION TO SANDY'S STATEMENT :
BY f SANDY MEANS KINETIC FRICTION.........
ROLLING FRICTION IS NOT ZERO.....WITHOUT FRICTION HOW CAN A TORQUE BE GENERATED TO KEEP IT ROLLING YAAR ???
11ya...
so ....
fkinetic = 0....(ans)
N.B. frolling ≠0
@aveek now thats a complete answer... rite??
