Tension of two strings/picture frame

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The discussion revolves around solving a physics problem involving a picture frame suspended by two strings at specific angles. The user successfully calculated the tension in string 2 as 0.7288 N but struggled with determining the weight of the picture. They attempted to use the tension value in their equations but arrived at an incorrect weight of 0.2335 N. Questions were raised about the negative sign in the equations and the multiplication of the weight by 9.8, which is the acceleration due to gravity. Clarification on these points is sought to resolve the misunderstanding and correctly calculate the weight.
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Homework Statement


Hey guys and girls I have tried to solve this one but I got part (b) wrong any help would be awesome :)

A picture hangs on the wall suspended by two strings, as shown in Figure 6-24, with θ = 72°. The tension in string 1 is 2.0 N

there is a picture with two strings attached to a ceiling and a picture frame hanging beneath. The θ angle is on string one to the left and string to the right has an angle of 32 degrees.

a) calculate the force tension of string 2

b) What is the weight of the picture?

Homework Equations





The Attempt at a Solution



Since the forces are at equilibrium, i set net forces = 0.

the sum of Forces (x) = Force (string 2) - (string 1) = 0
Sum of Forces (y) = Force tension string 2 + Force tension string 1 - w*g = 0

I get two equations:
1) Force tension 1 cos 32 - 2.0 N cos 72 = 0
2) Force tension 2 sin 32 - 2.0 N sin 72 -(9.80 * w) = 0

solving for equation 1 i get Force of tension on string 2 = 0.7288 N which comes out as correct

However, I get part b) weight of the picture wrong

I put my Force of tension 2 into equation 2 to get weight

(0.5299)(0.7288) + 1.902 -9.80*w = 0
solving i get weight = 0.2335 N but that comes out as wrong. Help lol
 
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P944 said:
2) Force tension 2 sin 32 - 2.0 N sin 72 -(9.80 * w) = 0
Why the negative sign here? Aren't both vertical components of the tensions positive? Also, why are you multiplying the weight by 9.8?
 
Last edited:
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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