Question

you are able to change the direction of a compound wheel based on the angel you pull in. and at a specific angel you are able to stop it from rolling in any way.  assume the inner an outer radii of the wheel are 6 cm and 12 cm, respectively. Calculate the critical angle at which the wheel does not roll

Approach:

For this problem you just need to use torque concept.

- Draw the free body diagram.

- Determine the pivot point.

- Choice of the angle is your choice. Could be "the angle between the force and the horizontal line" or "the angle between the force and the vertical line"

- Then analyse the torque. You should find out that there are three cases that force can have with respect to the pivot point.

-- One case the force makes the toy turn clockwise

-- One case makes it turn counter-clockwise

-- Last case torque is zero

Hit: force is always tangent to the smaller circle.

Answer 1