Question

I'm on a boat. I have to raise a 6000 kg weight box from the water, but I only can 300 (N) Newton strength to pull up it.
The cylinder of radius 10 cm.
What is the radius of the wheel to raise my box?
(Sorry for my English, I've never had to speak about Physics in English.)

Answer 1

i'll try it.

Answer 2

is the box inside the water?

Answer 3

Yes, it is there.

Answer 4

what is the wheel? Can you give us a diagram?

Answer 5

Like these: http://upload.wikimedia.org/wikipedia/commons/thumb/e/e9/Four_pulleys.svg/600px-Four_pulleys.svg.png

Answer 6

is the box fully submerged? How far up does it have to be pulled?

Answer 7

I don't know where is the box exactly, and the time isn't specified. I need the ray of the weel.

Answer 8

ray of wheel is irrelevant for pulleys. According to the picture of pulleys, probably you want to know how many wheels you need to lift the mass, as the amount of wheels is the divider of the load's weight.

Answer 9

So, supposing the load is in the water, the load gets lift equal to the weight of the displaced water. We do not know what material is the load.
It could be 6000kg of isoprene, and thus floating on the water. It could be lead and sinking through the water.

Answer 10

but ok, we have to lift the load out of the water, not?
so, approximately you need for lifting F= m.g = 6000kg.9,8m/s^2 = 58800N
with force 300N
n = 58800N/300N=196 wheels

You could cut this cylinder into 196 pieces and construct a pulley with so many wheels, and a real long rope/cable/line

You could instead use the cilinder as a lever with fulcrum at 1/196 of total length away from the load.