What is the required force to lift oneself using movable pulleys?

[xX1SHOt]

1. Homework Statement

In the figure below, the man and the platform together weigh 780 N. The pulley can be modeled as frictionless. Determine how hard the man has to pull on the rope to lift himself steadily upward above the ground.

____________N



2. Homework Equations

I didn't use any until it said i was wrong but here is what it would be:

mg = T(1) + T(2)
T(1) = T(2)



3. The Attempt at a Solution

mg = 780 N = 2*T(1)

780 N / 2 = T(1)

390 N = T(1)

I first entered 390 and it was wrong, then I tried 391 to steadily move it upward. Both were wrong. Any help?

 

[xX1SHOt]

cant anyone help

 

[The_ArtofScience]

I believe the answer is simply T = 780 N.

T - mg = m(0)
T = mg = 780 N

They didn't give you any value for the acceleration which if they did would've changed a lot.

 

[xX1SHOt]

nevermind i figured it out, thanks