Can anyone help with my physics homework?

F

Felicity

New member
A uniform plant of length 5m rests horizontally on two bricks that are 0.5m from either end. A child of weight 200N stands on one end of the plank and causes the other end to lift, so it is no longer supported at that end. Calculate the weight of the plank.

Thanks!!!
 
The weight of the plant must be given or the unit weight of the plant per meter must be given
the child must stand outside the beam in order to tilt the plant
so that there is no reaction on the other support
 
Suppose the weight of the plank is W. This weight acts downwards at the plank's center of mass. which is at the center of the plank. U first need to draw a free body diagram. In the fbd, draw a weight of 200N acting downward at one of the ends. W N acts downward at the center of mass of the plank. as the other end lifts slightly, the normal reaction at that end is 0 and the normal reaction at the other brick is N newtons. Now to calculate the magnitude of W, we may choose any point as origin and use the balance of torques equation. However it is easiest if we choose the brick on which the plank is balanced as origin. That way, we avoid having to calculate the magnitude of N.

Apply the balance of torques. Then u can calculate the magnitude of W
 
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