I need help with a physics problem.?

Question

I gotta get the acceleration of the system and the tension of all ropes.

http://img50.imageshack.us/img50/2975/75872945ss9.jpg

Answers are:

a = 3.5 m/second squared, T1 = 27N and T2 = 32, 5N

Can I get this with all the proceadures? If you can't do a symbol, like me with second squared, write it out. For example:

28 rabbits per square cubed. Get it?

P.S: Since it's Physics in another language, Froz = the friction of the surface, idk wut it's called in english. Maybe static friction...but not 100% sure.

Oh and I have my reasons for not putting this in the original language.

Answer 1

First, you can get rid of a couple of variables.  Tv1 is the same as TA (since they are the same rope); and Tv2 is the same as TR (since they are the same rope).  Call them T1 and T2.

So, use F=ma for each mass separately:

Mass 1 (on left):

F_net = ma

(T1 - (2.0kg)(g)) = (2.0kg)a

Mass 2 (on table):

F_net = ma

(T2 - T1 - Froz) = (m2)(a)

or, since Froz = (μ)(F_normal) = (μ)(m2)(g):

(T2 - T1 - (μ)(m2)(g)) = (m2)(a)

Mass 3 (on right):

F_net = ma

((5.0kg)(g) - T2) = (5.0kg)(a)

Now you have 3 equations.  The quantities "g" and "μ" are given, so now the unknowns are:

T1, T2, a, m2

That means 3 equations in 4 unknowns, which means you cannot find a unique solution.  If you were given another one of those quantities (say, m2); then you could use algebra to solve for the remaining unknowns.