Simple Tension ProblemCan you confirm that I am doing it Right?

[MJC8719]

A picture hangs on the wall suspended by two strings, as shown in Figure 6-24, with = 72°. The tension in string 1 is 2.0 N. Tha angle of the second string is 32°.

So because I am an idiot and keep getting sin and cos confused (stupid mistake), I have one last submission on this problem and was hoping someone could tell me whether or not I am following the correct path.

Verify your answer to part (a) by calculating the tension in string 2.
Since the forces of x will cancel one another, you know
2cos72 = xcos32
x = .72877N


(c) What is the weight of the picture

The weight T=mg would just be the sum of the tensions in the Y direction divided by 9.8 correct??

In this case M = 2sin72 + .7287sin32/9.8
= .236

 

[Doc Al]

Whether your sines and cosines are correct depends on where the angles are measured from. If string 1 is 72 degrees from the horizontal, then you have it straight. (We can't see the diagram, so it's up to you.)

For part (c) realize that they asked for the weight, not the mass.

 

[MJC8719]

So that means the final weight of the picture would be
W = mg
= .236(9.8)
= 2.3128N

And yes, the angles are from the horizontal

thanks

 

[Doc Al]

That sounds about right. But please don't divide by 9.8 only to then immediately multiply by 9.8. (And review your calculations for round-off errors, being sure to round off to the appropriate number of digits.)