Easiest way for two men to lift a pipe

  • Thread starter Thread starter voyager221
  • Start date Start date
  • Tags Tags
    Lift Pipe
AI Thread Summary
When lifting a pipe with a rope, the tension and angle of the rope significantly affect the effort required by the lifters. A loose rope allows for a more favorable distribution of weight, making it easier to lift compared to a tightly knotted rope. The angle of the rope, denoted as theta, influences the force each lifter must exert, with a longer rope reducing the effective weight each person feels. The calculations suggest that minimizing the angle theta reduces the force needed, contradicting the initial observation. Overall, the mechanics of rope tension and angle play a crucial role in lifting efficiency.
voyager221
Messages
18
Reaction score
0
If rope is wrapped around a pipe and two men are lifting it up why is it easier to lift when the rope is loose around the pipe (A) and harder when the rope is tied tightly to the pipe in a knot at both ends (B) ?

I presumed this was because on A the weight is less concentrated?
 
Physics news on Phys.org
I'm guessing a bit at the diagram...
Rope attached to one end of pipe, rises at angle theta to horizontal to first porter, proceeds horizontal to second porter, descends at angle theta to attach to other end of pipe. And the question is, why does a longer rope (greater theta) make it easier on the porters?
Pipe weight W, tension in rope T = W cosec(theta)/2.
To balance the tension locally, each porter has to pull at angle theta/2 to vertical with force F = 2T sin(theta/2).
Thus F = W sec(theta/2)/2. This is minimised when theta is 0.
So it doesn't support your observation.
Maybe I have the diagram wrong.
 
Last edited:

Thread 'Derivation of Hamilton's Principle: Questions'

I have recently been really interested in the derivation of Hamiltons Principle. On my research I found that with the term ##m \cdot \frac{d}{dt} (\frac{dr}{dt} \cdot \delta r) = 0## (1) one may derivate ##\delta \int (T - V) dt = 0## (2). The derivation itself I understood quiet good, but what I don't understand is where the equation (1) came from, because in my research it was just given and not derived from anywhere. Does anybody know where (1) comes from or why from it the...
View full post »

Similar threads

I 1:1 versus 2:1 Mechanical Advantage debate
Replies
20
Views
314
Question about lifting water through a water pipe
Replies
4
Views
2K
I Understanding the physics of a bosun's chair and mechanical advantage
Replies
6
Views
3K
Why is it so much easier to lift a spinning gyro than if stationary?
2
Replies
67
Views
23K
Why two men can't lift a 2 ton car but can push same car
Replies
10
Views
5K
Why Does Pulley Require Less Work to Lift Mass?
Replies
6
Views
7K
Pulley Carrying Capacity: Can It Handle 150 lbs?
Replies
9
Views
3K
Best way to measure non-thermal expansion of a pipe
Replies
6
Views
2K
I Minimize supported weight of a water pipe
Replies
28
Views
3K
HVAC Understanding the movement of a fluid in a vertical pipe
Replies
10
Views
6K

Hot Threads

Recent Insights

Back
Top