Just wanted to disclaim this problem — it is homework. However, I am not asking for the solution, I am wondering if anyone can tell me what I may be doing wrong in solving this specific tension problem.
The problem is described by this picture:
Now, assuming masses of the cords suspending the mass $M$ are insignificant, the question is what is the value of $T_2$ (given specific values of $\theta$ and the mass of $M$).
So, here's my solution:
Since the object is in rest, by $F = ma$ and $a=g$,
$$ mg = T_1 \sin(\theta) $$
and
$$ T_2 = T_1 \cos(\theta) $$
Therefore,
$$ T_1 = \frac{mg}{\sin(\theta)} $$
and, furthermore,
$$ T_2 = \frac{mg \cos(\theta)}{\sin(\theta)} = mg \cot(\theta). $$
So, that is my final solution, however, multiple sources are telling me it is wrong (these sources being my 1. teacher's automated grading software and 2. a textbook answer to the same problem, with different mass and theta value and a value different than what I am finding).
Is this a correct means of reaching the conclusion?
Best Answer
Maybe I am missing something simple, but I cannot find any errors in your solution.