Pulleys and Mass

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yeah but thats the thing for A i am getting the tension to be zero.
The equation i have for A is ma=t is this right .
Also for pulley C i got 30N

MrWarlock616

edit: this is not correct, because there are 3 tensions, 2 of which are the same.
No it's not. a=0, and there are 3 tensions, 2 of which are the same.

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ok i got 15N...would this be the force the man would use to pull the box ?
Also why did we not use pulley B?

MrWarlock616

Sorry I edited my post above, so 15 N is wrong. The diagram in my head was different.

Pulley B is just stationary and is acted upon by another force apart from the 2 different tensions, so it just gives us another unneeded unknown.

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ahh ok so with the new ones i got the tension for pulley C 24N and Pulley A to be 15N.
now would 15N be the force that the man must pull with?

MrWarlock616

24 N is correct and this is the tension in the green rope. 15 N is not correct. Check your equations..

The tension in the red rope is the force that the man must pull it with.

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sorry i meant to write 12N..my bad
and this would be the force the man would have to use right

MrWarlock616

Yes. The force must be greater than 12 N to lift it up.

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Yes i understand..ok Thanks a lot u really walked me through this question.
Thank u sir Have a good day :)

MrWarlock616

You're welcome!