Answer:
0.1426 N
Explanation:
A chain of uniform mass density is suspended between two poles 30 cm apart. The geometry of the problem is such that the left support only supplies a horizontal force on the chain. The right support must both balance that horizontal force and supply a vertical force that balances the weight of the chain.
Magnitude of forces
For some tension T in the chain at the right support, the vertical force will be ...
vertical force = T·sin(α) = W . . . . . matches the weight (W) of the chain
for some angle α between the horizontal and the chain at the right pole.
The corresponding horizontal force is ...
horizontal force = T·cos(α)
This force balances the horizontal force at the left support pole. In terms of W, this force is ...
horizontal force = W/sin(α)·cos(α) = W/tan(α)
Angle
The curve assumed by a chain of uniform mass density can be demonstrated to be a catenary. For supports 30 cm apart, its equation can be described by ...
y = 30·cosh(x/30)
The diagram shows that y=4 for x=0, so we need to subtract 26 cm from this:
y = 30·cosh(x/30) -26
The slope of the curve at any point is the derivative of this function:
y' = 30(1/30)(sinh(x/30)) = sinh(x/30)
At the right support, the slope of the curve is ...
y' = sinh(30/30) = sinh(1) ≈ 1.1752012
This is the tangent of the angle that the curve makes with the horizontal at the right support.
tan(α) = 1.1752012
Note, you can see from the grid squares on the graph that the slope at the right support is slightly more than 1.
Weight
The weight of the chain is the product of its mass and the acceleration due to gravity:
W = ma = (0.0171 kg)(9.8 m/s²) = 0.16758 N
Force on the Pole
Then the force on the left-side pole is ...
horizontal force = W/tan(α) = (0.16758 N)/1.1752012
horizontal force ≈ 0.1426 N
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Additional comment
The attached graph is a plot of the catenary curve we have assumed for the gold chain. We have attempted to match the vertical height on the left side, but we note that there seems to be a small discrepancy at the right side. The graph in the problem statement seems to show the right attach point at about y=21, not 20.3.