Finding Tension in a Simple Crane System

Click For Summary
The discussion revolves around calculating the tension in a horizontal support cable of a simple crane system involving a rigid rod, a mass, and a pulley. Participants emphasize the need to identify all forces acting on the rod, including the weight of the mass and the tension in the cable. One user incorrectly suggests that the tension can be derived from the weight component along the rod, while another points out the importance of considering the net moment about the rod. The absence of the rod's mass in the problem is noted as a complicating factor. Overall, the conversation highlights the challenges in applying equilibrium principles to solve for tension in this mechanical setup.
XxseanxX_22@h
Messages
4
Reaction score
0

Homework Statement


A simple crane consists of a rigid rod that is hinged to a wall at one end and tied to the wall with a horizontal cable at the other end. The rod makes an angle θ to the wall. At the same end to which the cable is attached there is also a frictionless pulley. The rope that is looped over this pulley is attached to a mass m at one end and is held at the other end so that the weight hangs in equilibrium. Given that the gravitational field is g, what is the tension, T in the horizontal support cable?
 
Physics news on Phys.org
Hi XxseanxX_22@h! :smile:

Show us what you've tried, and where you're stuck, and then we'll know how to help. :wink:
 


well i got mgtanθ
 
XxseanxX_22@h said:
well i got mgtanθ

hmm … that's not even an equation, that's only the component of the weight of the mass m along the rod.

(btw, what's the mass of the rod itself?)

Hint: in problems like this, start by saying how many forces there are on the rod, and what they are. :smile:
 


I know this is another old post, but I found that XxseanxX_22@h has posted identical problems in the past that I have right now, I'm thinking he was potentially in the same class I am in now xD (btw, it is just coincidence we have the same name :S)

I am stuck, for net forces I have found that T=sintheta and 2mg=costheta. I'm not sure if those are right, but I'm also having trouble finding net moment about the rod. Any help?

edit: it doesn't actually give you the mass of the rod in the question
 
Last edited:


Any help please? Would be greatly appreciated!
 

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?
View full post »

Similar threads

Luffing Jib Load, With and Without Sheave Pulley
  • · Replies 3 ·
Replies
3
Views
2K
Tension and net torque in a cable
  • · Replies 10 ·
Replies
10
Views
5K
Newton's Second Law (Pulley Sustem)
  • · Replies 3 ·
Replies
3
Views
2K
What is the Time to Pivot the Rod with a Spinning Disk?
  • · Replies 2 ·
Replies
2
Views
1K
What are the tensions on two cables holding a girder hanging from a crane?
  • · Replies 14 ·
Replies
14
Views
3K
Torque and Rotational Equilibrium with a slanted Rod/Cable
  • · Replies 7 ·
Replies
7
Views
3K
Problem with pulleys - two fixed and one movable
  • · Replies 22 ·
Replies
22
Views
1K
Tension in a deformed cylindrical bag on a surface
  • · Replies 18 ·
Replies
18
Views
2K
Finding the tension of two cables holding an object at rest
  • · Replies 7 ·
Replies
7
Views
2K
Flag pole finding horizontal force component at hinge.
  • · Replies 1 ·
Replies
1
Views
3K