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- Homework Statement
- Three bodies are conected by ideal ropes. The mass of the smallest body is ##10 kg##. The coefficient of static friction between the bodies and the surface is ##0.3## and they are pulled to the right by a ##60 N## force. Determine the tension acting on each rope.

- Relevant Equations
- Newton's equations

I called the smallest body ##1## and the biggest ##3##. All of them are disturbed by horizontal forces. So the free body diagrams are

For ##1##

##-T_1 -Fr_1 +F=10a##

For ##2##

##T_1 -T_2 -Fr_2=20a##

For ##3##

##T_2 -Fr_3=30a##

Then, if I consider ##a=0## and I solve for ##1## I get ##T_1=30 N##, and then if I plug that value in ##2## I get ##T_2=-30 N##. But why the signs of both tensions are different?

And then if I tried to find ##T_2## in ##3## I get ##T_2=90##, and clearly that's different from the value calculated in ##2##.

For ##1##

##-T_1 -Fr_1 +F=10a##

For ##2##

##T_1 -T_2 -Fr_2=20a##

For ##3##

##T_2 -Fr_3=30a##

Then, if I consider ##a=0## and I solve for ##1## I get ##T_1=30 N##, and then if I plug that value in ##2## I get ##T_2=-30 N##. But why the signs of both tensions are different?

And then if I tried to find ##T_2## in ##3## I get ##T_2=90##, and clearly that's different from the value calculated in ##2##.