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Please see the attachment and answer problem 3 only.

A uniform circular plate of radius 300 mm and mass 26 kg is supported by three vertical wires that are equally spaced arround its edge (see the attachment). A small 3 kg block E is placed on the plate at D and is then slowly moved along the diameter CD until it reaches C. a) Plot tension in wires A and C as function of a, where a is the distance of the block from D, b) Determine the value of a for which the tension in wires A and C is minimum.

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Solution Preview

Fig. shows all the forces acting on the system :

i) Weight of the circular plate (Mg) acting downwards at its centre.
ii) Weight of the block (mg) acting downwards.
iii) Tensions in the three wires TA, TB and TC (due to symmetry, TA = TB)

As the system is in equilibrium, moment of all the forces about an axis parallel to the x axis and passing through point C will be zero (Moment of a force about an axis is given by the product of the force and the perpendicular distance of the axis from the line of action of the force. Sign of the moment is taken as +ve if the force tends to rotate the object in counter clockwise direction and negative for clockwise direction).

From symmetry we note that the resultant of TA and TB (TA = TB) is 2TA and it acts on the Z axis at z = R/2. ...

Solution Summary

The expert determines the tensions in the wires. Step by step solution provided.