*24.  The drawing shows a bicycle wheel resting against a small step whose height is

h = 0.120 m. The weight and radius of the wheel are W = 25.0 N and r = 0.340 m, respectively. A horizontal force  is applied to the axle of the wheel. As the magnitude of  increases, there comes a time when the wheel just begins to rise up and loses contact with the ground. What is the magnitude of the force when this happens?

 

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Problem 24

Free Body Diagram is shown below

Take sum of torques at the point the step touches the wheel, that eliminates two torques

 

The diagram below is used to show the perpendicular distances for the torques

Since we are looking for when the wheel just starts to rise up N-> 0 so no torque due to normal force.

The perpendicular lever arm for the F force is R-h.

 

 

The perpendicular distance for the mg force is the other side of the right triangle

 

 

 

 

 

 

 

 

 

 

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This page last updated on January 11, 2020