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Course hero N4M.6 A board has one end wedged under a rock having a mass of 380 kg and is supported by another rock that touches the bottom side of the board at a point 85 cm from the end under the rock. The board is 4.5 m long, has a mass of about 22 kg, and projects essentially horizontally out over a river. Is it safe for an adult with a mass of 62 kg to stand at the unsupported end of the board

Answer :

okpalawalter8

Answer:

Therefore it is save to carry a 62kg adult

Explanation:

From the question we are told that:

Mass [tex]m=380kg[/tex]

Height of supporting Rock [tex]X=85cm[/tex]

Length of Board[tex]L_r=4.5m[/tex]

Mass of board [tex]M_b=22kg[/tex]

Mass of adult [tex]M_a=62[/tex]  

Generally the moment of balance about wedge part about  is mathematically given by

[tex]N -Q + R = Mg + mg[/tex]

[tex]0.85*N - Mg*2.25 - mg*(2.25 + x) = 0[/tex]

[tex]0.85*N = + Mg*2.25 + mg*(2.25 + x)[/tex]

where

[tex]N+R=4547[/tex]

therefore

[tex]N = 570.70588 + 1608.3529 + 714.823 x[/tex]

if N=0 at fallen person

[tex]x=3.04m[/tex]

Therefore it is save to carry a 62kg adult

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