Frank in Thailand
making mistakes so you don't have to...
One pulley will decrease the 200 meter to 100 meter, and the 20 kg potential energy doesn't get reduced by half.
There is some friction, and lifting the weight will use 10 kg, but double the amount of rope.
If the rope is wound on a motor / generator..
You are correct, it doesn't add potential energy, it looses a bit due friction.
It also doesn't take away potential energy.
The pulling force is less (half) the duration is longer (double)
Stored energy stays the same.
If it would be "free fall.." velocity increase due gravity, and with it potential energy..
Yes, 5 meters is less speed then 200 meter
And with it, less of a "bang" or a pull in the rope (before it hits the ground)
Just the initial pull of 20 kg is the same at 5 and 200 meters (if we don't try to calculate the slightly lower gravity at 200 meter)
And as it's a controlled drop / lowering of the weight, friction of the pulleys, additional weight of the ropes..
Adding 25% extra should compensate.
20 kg on 200 meter isn't doable.
25 kg on 5 meter is.
The efficiency (what was already not a good one) will be reduced.
But .. that isn't important (!!)
It's a crap of a "battery" that should only store energy that otherwise would be lost.
And it can keep it stored for decades without losses.
Gravity won't change much in a decade. (We all hope ?)
It does have it's uses.
And as a DIY project to learn and for fun, sure!!
Pulleys will help you not to build a tower of 200 meter.
And still have de desired end result.
There is some friction, and lifting the weight will use 10 kg, but double the amount of rope.
If the rope is wound on a motor / generator..
You are correct, it doesn't add potential energy, it looses a bit due friction.
It also doesn't take away potential energy.
The pulling force is less (half) the duration is longer (double)
Stored energy stays the same.
If it would be "free fall.." velocity increase due gravity, and with it potential energy..
Yes, 5 meters is less speed then 200 meter
And with it, less of a "bang" or a pull in the rope (before it hits the ground)
Just the initial pull of 20 kg is the same at 5 and 200 meters (if we don't try to calculate the slightly lower gravity at 200 meter)
And as it's a controlled drop / lowering of the weight, friction of the pulleys, additional weight of the ropes..
Adding 25% extra should compensate.
20 kg on 200 meter isn't doable.
25 kg on 5 meter is.
The efficiency (what was already not a good one) will be reduced.
But .. that isn't important (!!)
It's a crap of a "battery" that should only store energy that otherwise would be lost.
And it can keep it stored for decades without losses.
Gravity won't change much in a decade. (We all hope ?)
It does have it's uses.
And as a DIY project to learn and for fun, sure!!
Pulleys will help you not to build a tower of 200 meter.
And still have de desired end result.