# CIE AS level physics

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#1
Hi,

0
1 month ago
#2
Hi,

You don't say what your doubt is or what answer you are getting, and how you got it.

The answer is found by taking moments about the pivot point and equating the moment of F to the moment of W.
The pivot point is where the cylinder touches the step.
The value of F to move the cylinder would effectively need to be ever so slightly greater that this. The value found is the so called 'minimum' value.
Did you do that?
Last edited by Stonebridge; 1 month ago
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#3
Oh, I'm sorry for not being specific. I meant that I don't know how to do it. An explanation of the steps to get the correct answer (that is B) would be appreciated
0
1 month ago
#4
Oh, I'm sorry for not being specific. I meant that I don't know how to do it. An explanation of the steps to get the correct answer (that is B) would be appreciated
AS I stated in my first reply, the way to do this is to use (equate) moments of a force about a pivot. Have you studied this?
The moment of a force about a point is that force times the perpendicular distance of that force from the pivot.
I have marked those two distances x (for W) and y (for F)
So the method involves using geometry to get an expression for those two distances, x and y, in terms of r and then equating the (force times that distance) for the 2 forces.
Last edited by Stonebridge; 1 month ago
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