- #1
I have to find the speed that the end of the arm goes. Can anyone
Click For Summary
Discussion Overview
The discussion revolves around calculating the speed of the end of a pivoted arm under the influence of a spring force. Participants explore the mechanics involved, including the application of Hooke's law and conservation of energy principles. The context includes theoretical and mathematical reasoning related to the dynamics of the system described in a diagram.
Discussion Character
- Exploratory
- Technical explanation
- Mathematical reasoning
Main Points Raised
- One participant expresses confusion about the problem, noting that the diagram only shows a rod and a spring without additional context.
- Another participant suggests using Hooke's law to calculate the force on the bar and then determining the moment to find the instantaneous acceleration, which could lead to velocity over time.
- A later reply provides specific parameters of the system, including the force applied, weight of the arm, and pivot distances, and proposes that the problem can be approached through conservation of energy.
- This participant indicates that potential energy of the spring can be calculated at the start and equated to kinetic energy to find the angular velocity and subsequently the linear velocity at the arm's end.
Areas of Agreement / Disagreement
Participants do not reach a consensus on the approach to solving the problem, with differing interpretations of the question and methods suggested for calculation.
Contextual Notes
The discussion lacks clarity on certain assumptions, such as the initial conditions of the system and the specific relationships between the forces and motion involved. There are also unresolved mathematical steps in the proposed solutions.
Who May Find This Useful
Individuals interested in dynamics, mechanics, and energy conservation principles may find the discussion relevant, particularly those working on similar problems involving pivoted systems and spring forces.
- #2
tiny-tim
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poopforfood said:
Hi poopforfood!
I don't understand
…all the diagram shows is a rod pivoted about its centre, and a spring which has one end fixed, and the other end attached perpendicularly to one end of the bar …
what is the rest of the question?
- #3
minger
Science Advisor
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I suppose that given a certain lower end position, x, you could calculate the force on the bar by the spring using Hooke's law. This force can then be used to calculate the moment, and given mass properties of the bar, instantaneous acceleration of the bar. Integrating could give you velocity as a function of time.
...I think.
- #4
poopforfood
- 13
- 0
sorry So I have a spring being extended at the top with a force of 51765 lbf being applied to the arm. The arm weighs approximately 2.1 lbs and is 3 feet long. The pivot point is 1 foot from the top and 2 feet at the bottom. Can anyone help me find the final velocity at the bottom point in the arm
- #5
tiny-tim
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Hi poopforfood!
(just got up :zzz: …)
ahh! ok, then this is a conservation of energy question …
find the potential energy of the spring at the start (when the kinetic energy is zero), and then find what the angular velocity must be when the PE is zero and it's all KE (from which you can get the velocity at the bottom).
(just got up :zzz: …)
poopforfood said:
ahh! ok, then this is a conservation of energy question …
find the potential energy of the spring at the start (when the kinetic energy is zero), and then find what the angular velocity must be when the PE is zero and it's all KE (from which you can get the velocity at the bottom).
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