Check my answers

Just answered it

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You should look again at Q5.

 

(Hint: If the tension equals the weight, then the net force is zero.  If the net force is zero the object isn't accelerating.)

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so the answer must be  B 

right ? 

That's correct!

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thank you Alan 

 

I have another question here 

 

http://web2.0calc.com/questions/work-done-by-force