3 The diagram shows a uniform beam AB , of weight 80 N and length 7 m , resting in equilibrium in a vertical plane. The end A is in contact with a rough vertical wall, and the angle between the beam and the upward vertical is \(60 ^ { \circ }\). The beam is supported by a smooth peg at a point C , where \(\mathrm { AC } = 2 \mathrm {~m}\).
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- Complete the diagram in the Printed Answer Booklet to show all the forces acting on the beam.
- Show that the magnitude of the frictional force exerted on the beam by the wall is 25 N .
- Hence determine the magnitude of the total contact force exerted on the beam by the wall.
- Determine the direction of the total contact force exerted on the beam by the wall.
The coefficient of friction between the beam and the wall is \(\mu\).
- Find the range of possible values for \(\mu\).
- Explain how your answer to part (b)(ii) would change if the peg were situated closer to A but the angle between the beam and the upward vertical remained at \(60 ^ { \circ }\).