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As shown, a server at a restaurant is carrying a tray that has a glass of water

ID: 1921169 • Letter: A

Question

As shown, a server at a restaurant is carrying a tray that has a glass of water resting on it. (Figure 3) The glass and tray exert a force with magnitude F1 = 13.0N on the server's hand. If l1 = 0.441m , l2 = 0.349m , l3 = 0.151m , ?1 = 165?, and ?2 = 130?, what is the moment of force about the shoulder joint at point A? Assume that moments acting in the counterclockwise direction about point A are positive whereas moments acting in the clockwise direction are negative

As shown, a server at a restaurant is carrying a tray that has a glass of water resting on it. (Figure 3) The glass and tray exert a force with magnitude F1 = 13.0N on the server's hand. If l1 = 0.441m , l2 = 0.349m , l3 = 0.151m , ?1 = 165?, and ?2 = 130?, what is the moment of force about the shoulder joint at point A? Assume that moments acting in the counterclockwise direction about point A are positive whereas moments acting in the clockwise direction are negative

Explanation / Answer

The vector components of the different distances are
(0.441*cos165,0.441sin165)
(0.349cos50, 0.349sin50)
(0.151cos0, 0.15sin0)

the force position is (- 0.112867,1.29)

the sum of the x components is the perpendicular distance of the force from A = 0.112867
The force is 13 N, the moment is 13*0.112867 = 1.467Nm