The load of an object on a pivot

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In summary, the conversation focused on determining the load on a 3.2m platform that weighs 175kg, with one end resting on the ground and the other on a pivoting bolt 2.5m in the air. The purpose was to figure out what force would be required to lift the end that is on the ground 4.5m in the air, in order to choose a suitable winch or hoist. It was established that the load would be half the weight of the platform, regardless of the angle at which the force is applied, and that a winch with a SWL of 125kg would be sufficient. The conversation also discussed the challenges of keeping the cable at a vertical angle and suggested creating
  • #1
simonwait
Hi

I have a 3.2m platform which weighs 175Kg. One end of the platform is touching the floor but the other end is on a pivoting bolt 2.5m in the air.

I need to figure out what the "load" would be on the end which is on the floor when I try to lift that end 4.5m in the air. Basically so I can spec a winch or hoist to lift it.
 
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  • #2
simonwait said:
Hi

I have a 3.2m platform which weighs 175Kg. One end of the platform is touching the floor but the other end is on a pivoting bolt 2.5m in the air.

I need to figure out what the "load" would be on the end which is on the floor when I try to lift that end 4.5m in the air. Basically so I can spec a winch or hoist to lift it.
Do you mean, what force is required to lift it at the free end?
It depends on the angle at which you apply the force. If you pull straight up, it will be half the weight of theplatform, regardless of the platform angle.
If you pull at right angles to the platform it will be less at first but will increase until the platform is level. At that point it will once again be half the weight of the platform. After that it will reduce again.
 
  • #3
OK great.

Yeah meant lifting the free end

Because of how it moves as its lifted then i would expect about 2 degrees either side of a direct lift vertically but based on it therefore not being far off then i will assume 1/2 the weight which is well within the limits of the winch I am looking at with an SWL of 125kg.

Thanks for your help
 
  • #4
simonwait said:
OK great.

Yeah meant lifting the free end

Because of how it moves as its lifted then i would expect about 2 degrees either side of a direct lift vertically but based on it therefore not being far off then i will assume 1/2 the weight which is well within the limits of the winch I am looking at with an SWL of 125kg.

Thanks for your help
Wait a moment...
With the lengths you quoted, you might have trouble keeping the cable within a few degrees of vertical. How high is the top of the cable?
 
  • #5
When the platform is down the cable is paid out about 14m from the drop point

Its also about 250mm further away from the pivot than the end of the platform so there is about of an arc.
 
  • #6
simonwait said:
Its also about 250mm further away from the pivot than the end of the platform
Is that when the platform is resting on the ground or when it is horizontal?
 
  • #7
When its on the ground
 
  • #8
simonwait said:
When its on the ground
Ok.
In general, finding the max load on the cable is quite a tricky optimisation problem, but with that 14m height I think you are ok.
 
  • #9
It may be worth while doing a scale drawing (for both conditions) and checking that the angles are near enough 90 degrees. (If you don't want to get involved with the Trig.) If the angle gets as low as 80 degrees, there's only a couple of percent of difference. 45 degrees will only make a force 40% more.
Btw, has it been established that the platform is uniform? Also, what will be on the platform? With that weight be significant?
 

1. What is the load of an object on a pivot?

The load of an object on a pivot refers to the weight or force exerted on the pivot point by the object. It is the amount of downward force that the object applies to the pivot.

2. How is the load of an object on a pivot calculated?

The load of an object on a pivot can be calculated using the formula L = F x d, where L is the load, F is the force exerted by the object, and d is the distance from the pivot point to the object's center of mass. This calculation takes into account both the magnitude and direction of the force.

3. What factors can affect the load of an object on a pivot?

The load of an object on a pivot can be affected by several factors, including the weight of the object, the distance from the pivot point to the object's center of mass, and the angle at which the object is placed on the pivot. Other external forces such as friction and air resistance may also impact the load.

4. Why is it important to consider the load of an object on a pivot?

Considering the load of an object on a pivot is important because it can help determine the stability and balance of the object. If the load is too heavy or unbalanced, it may cause the object to tip or fall, potentially causing damage or injury. Understanding the load can also aid in the design and construction of structures that use pivots, such as bridges and cranes.

5. How can the load of an object on a pivot be adjusted?

The load of an object on a pivot can be adjusted by changing the force or weight of the object, altering the distance from the pivot point, or adjusting the position of the pivot itself. For example, moving the pivot closer to the object's center of mass can decrease the load, while moving it further away can increase the load. Additionally, changing the angle of the object on the pivot may also affect the load.

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