- #61
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That is the same as the general equation I obtained.Jpyhsics said:
Finding the acceleration of two masses on a pulley system
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Homework Help Overview
The problem involves two blocks connected by a massless pulley and string, with one block on a surface and the other suspended. The system is in equilibrium but is about to slide due to an increase in the mass of the suspended block. The surface is accelerating horizontally, and the problem asks for the acceleration of the block on the surface.
Discussion Character
- Mixed
Approaches and Questions Raised
- Participants discuss the implications of the given horizontal acceleration and how it relates to the accelerations of the two masses. There are questions about the role of friction and the relationship between the accelerations of the masses and the surface.
Discussion Status
Participants are exploring the relationships between the forces acting on the masses and the surface. Some have offered insights into the implications of the string's constant length and the nature of the forces involved, while others are questioning the assumptions about friction and acceleration.
Contextual Notes
There is uncertainty regarding the coefficient of friction and its impact on the system, as well as the specific arrangement of the masses in relation to the pulley. Participants are also considering the effects of the surface's acceleration on the hanging mass.
- #62
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FriedChicken885
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haruspex said:
Okay, thank you very very very much for all of your help!
- #64
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Should one not consider that the tension supporting the hanging mass is no longer parallel to the vertical side of the table but at an angle?
Also, I think that ##g=9.81 ~m/s^2## in the expression posted by OP in #62 should be replaced by an effective acceleration. This problem can be solved quite simply in the accelerated frame with additional fictitious horizontal forces ##-m_i\vec a_0## acting on masses ##m_i##. Here, ##\vec a_0## is the given horizontal acceleration of the table.
Also, I think that ##g=9.81 ~m/s^2## in the expression posted by OP in #62 should be replaced by an effective acceleration. This problem can be solved quite simply in the accelerated frame with additional fictitious horizontal forces ##-m_i\vec a_0## acting on masses ##m_i##. Here, ##\vec a_0## is the given horizontal acceleration of the table.
- #65
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we are asked for the accelerations immediately after the surface has started to accelerate. The string is still vertical.kuruman said:
I don't see why. Do you get a different answer? If so, please post your solution.kuruman said:
- #66
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I don't get a different answer, but I am bothered by the fact that one writes the same equation for the hanging mass whether the pulley supporting it accelerates or not. When the pulley accelerates, the hanging mass must have a horizontal acceleration at t = 0 because its horizontal position changes a moment later. Should this not affect the tension? I need to think about this some more.
On Edit: OK, I got it. At t = 0 the horizontal acceleration is instantaneously zero and then changes as it reaches a constant value in the steady state.
On Edit: OK, I got it. At t = 0 the horizontal acceleration is instantaneously zero and then changes as it reaches a constant value in the steady state.
Last edited:
- #67
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Right.kuruman said:
Or maybe oscillates.kuruman said:
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