Towing Sleds - Finding Tensions

[Twiggy92]

Three sleds are being pulled horizontally on a frictionless horizontal ice using horizontal ropes. The pull is a magnitude of 125 N. Find (a) the acceleration of the system and (b) the tension in ropes A and B (see diagram below)

[30 kg sled]---rope B---[20 kg sled]---rope A---[10 kg sled]----> 125 N force

F = total mass * a
Tension = m*a


F = m*a
125 = 60*a
a= 2.08 m/s^2

Using the T=m*a equation, which sleds do I plug in for m to get the tension in each rope?

 

[azizlwl]

Each sledge is experiencing a net force that makes it moves at 2.08 m/s^2

 

[Yukoel]

Hello Twiggy92
Welcome to physics forums ! :)
In your case each block is moving with an acceleration you calculated right?There are two ways to handle your problem
(1) The same method you used.Try removing the penultimate block and apply your force equation.
(2) Isolate each and every block and analyse the forces as pointed out by the member azizlwl.
Try both and let us know if you get the right answer .:)
regards
Yukoel