Newton's Law Problems: Solve My 4 Problems

[the whizz]

here is my 4 problems.


attached is my attempt at #2...any input would be great.

 

[the whizz]

are these images viewable...it'd be a pain to type out the problems.

 

[the whizz]

ok here are my solutions to all four problems...if anyone can take a look i would love it.

thanks

 

[PhanthomJay]

here is my 4 problems.


attached is my attempt at #2...any input would be great.

You shouldn't be looking at the system of 3 masses together, because it is confusing to identify the "net' force acting, and if by chance you get the right combination of forces, the solution is not in the spirit of Newton's 2nd Law. Instead, look at each mass separately, identify the forces acting on each, and use Newton 2 on each. You're going to have to do this anyway to find the tensions. You'll end up with 3 equations which you can solve for the 3 unknowns, T1, T2, and 'a'. I also note that your forces on mass 3 are not directed in the proper direction, although you seem nonethelseess to have correctly identified the forces acting up the plane.

 

[the whizz]

and #4