As part of my physics homework (which I do not need the answer for, as I did it by hand, and got the correct $$\frac{m_1 g-m_2 g \sin(\theta)}{-m_1-m_2}$$ as the answer) I would have liked to have solved the following system of equations as shown (i.e. put $a_1$ as Subscript[a,1]
and not a1
or something similar. The equations that I wanted to solve were:
Subscript[m, 2] Subscript[a, 2 x] == T - Subscript[m, 2] g Sin[\[Theta]]
Subscript[m, 1] Subscript[a, 1 y] == T - Subscript[m, 1] g
Subscript[a, 2 x] == -Subscript[a, 1 y]
I tried the following, and was given {}
as the answer (which is clearly false):
Solve[Subscript[m, 2] Subscript[a, 2 x] ==
T - Subscript[m, 2] g Sin[\[Theta]] &&
Subscript[m, 1] Subscript[a, 1 y] == T - Subscript[m, 1] g &&
Subscript[a, 2 x] == -Subscript[a, 1 y], Subscript[a, 1 y]]
It seems that there at least two problems with the equations that I am asking it to solve.
I do not think that it is treating $a_{1y}$ as a variable. When I typed a in the part of solve that asks for the variables that I am solving for, all terms that have
a
in them light up as blue, but when I enter the subscript, it loses that highlighting.It would seem (at least to me) that a perfectly valid answer to
Solve
would be $-a_{2x}$ but that would be a useless answer, as I want the answer in terms of $m_1 , m_2 , g, \theta$ and not in terms of other "compound variables"
Note: When I tried a "subscript-less" version (Solve[m2 a2x == T - m2 g Sin[\[Theta]] && m1 a1y == T - m1 g &&
a2x == -a1y, a1y]
I still got {}
as the answer. Using Mathematica 8.
What is going on, and how can I enter the equations normally, and solve for them in terms of specific variables?