As shown, a server at a restaurant is carrying a tray that has a glass of water
ID: 1828735 • 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 F 1 = 7.40lb lb on the server's hand. If L1 = 1.40ft ft , L2= 1.10ft , L3 = 0.250 ft , ? 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.
Express your answer numerically in pound-feet to three significant figures.
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 F 1 = 7.40lb lb on the server's hand. If L1 = 1.40ft ft , L2= 1.10ft , L3 = 0.250 ft , ? 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
(1.40*cos165/1.40sin155)
(1.10cos50/1.10sin50)
(0.250cos0/0.250sin0)
the force position is (-1.35+0.707+0.25/0.591+0.842+0)=-0.393/1.433
the sum of the x components is the perpendicular distance of the force from A = 0.393
The force is 7.4 lb, the moment is 7.4*0.393 = 2.908 lb*ft
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