# Function of Counterweight

by primarygun
Tags: counterweight, function
 P: 234 What are the functions of counterweight in a lift system?
 HW Helper Sci Advisor P: 3,149 Use of a counterweight avoids having to lift so much weight! Less weight means less power consumed and lower cost.
 P: 284 In theory ( ideal ) a counterweight means that a system has NO net forces due to gravity and is balanced with no tendancy to move even tho' free to do so. This means a separate force applied does not have to do gravitational work ( lifting ) but only against friction . So for example if I suspend two 1 ton weights over a rope and pulley , which are balanced, then to move them does not require me to lift 1 or 2 tons . They still have inertia ( and resist moving ) but not due to weight , and if there is little friction then any applied force would move them but slowly if the force applied was small. in many cases a counter weight is used to reduce stresses in the frame -- a large crane is an example , where the horizontal arm with a lot of weight would twist the upright unless a counter or balancing weight is used. This changes the direction of stress to one of compression down the upright rather than bending it. Steel is very strong in compression but weak in bending. Ray
P: 234

## Function of Counterweight

So when the counterweight moves down, force applied by human is reduced.
When it moves up, force required to make the lift down is bigger, but it makes use of gravitational force.
Here, should I use energy instead of force?

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