A uniform plank of mass 10kg and length 10m rests on two supports, A and B as shown. A boy of weight 500N stands at a distance of 2m from A. Find the reaction forces U¹ and U² at the supports A and B respectively​

U² = 142.86 N

U¹ = 357.14 N

Explanation:

Taking summation of the moment about point A, we get the following equilibrium equation: (taking clockwise direction as positive)

where,

W = weight of boy = 500 N

U² = reaction ay B = ?

Therefore,

U² = 142.86 N

Now, taking summation of forces on the plank. Taking upward direction as positive, for equilibrium position:

U¹ = 357.14 N

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