nvm

[random1234]

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never mind, i figured it out 🙂

 

[Postictal Raiden]

boxes A, B, and C each have a mass of 10 kg. If the boxes are accelerated upward at 2 m/s^2, what is the tension T2?

I get that T2 = mg + ma + T3

So isn't that (10 * 10 = 100) + (10 * 2 = 20) + (100) = 220?

But the answer is C, 240, not B, 220.
Why is it 240?

Reading the question the way you posted it, I imagined the two boxes as one big 20kg box pulled upward by a rope.

F(net) = Tension in the rope - force of gravity
20 *2 (ma) = T - (20*10)
T = 40N + 200N = 240N

 

[random1234]

Yes that should have been the answer. EK wrote that the size is Box B, not Boxes B and C.