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A person carries a plank of wood 2.00 m long with one hand pushing down on it at one end with a force f1 and the other hand holding it up at .500 m from the end of the plank with force f2 . if the plank has a mass of 20.0 kg and its center of gravity is at the middle of the plank, what are the magnitudes of the forces f1 and f2 ?

Respuesta :

Edufirst

Answer:


F₁ = 4,120.2 N


F₂ = 3,924N


Explanation:



1) Balance of angular momentum around the end where F₁ is applied.


F₂ × 0.5m - F₁ × 0 = mass × g × 1m


⇒ F2 × 0.5 m= 20 kg × 9.81 m/s² × 1 m = 1,962 N×m


F₂ = 196.2 Nm / 0.5m = 3,924 N


2) Balance of forces


F₁ - F₂ = mg


F₁ = F₂ + mg = 3,924N + 20kg (9.81 m/s²) = 4,120.2 N

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