Tension in circular motion with connected masses

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Homework Help Overview

The discussion revolves around a problem involving two blocks connected by ropes, moving in circular motion on a frictionless table. The original poster presents the scenario with specific masses, rope lengths, and a period of motion, seeking to determine the tension in each rope while considering the forces acting on each mass.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants explore the forces acting on each mass, particularly questioning how tension behaves when multiple ropes are involved. There is an emphasis on the need for free body diagrams to clarify the forces at play.

Discussion Status

Participants are actively engaging with the problem, offering suggestions to analyze the forces and periods for each mass separately. There is a recognition of the interactions between the two masses and how they affect the tension in the ropes.

Contextual Notes

Participants note the assumption that all ropes are massless and the implications this has on the analysis of forces. There is also a focus on the relationships between the two rotating bodies and the fixed point of attachment.

Greenlime770
1. The problem statement, all variables, and given/known data
A block of mass m1 = 2.00kg is attached to a rope of length L1 = 0.50m, which is fixed at one end to a table. The mass moves in a horizontal circle supported by a frictionless table. A second block of mass m2 = 1.25kg is attached to the first mass by rope of length L2 = 0.75m. The mass also moves in a circle, as shown in the image. If the period of the motion is T = 15s, find the tension in each rope. (Assume all ropes are massless).

Image of Figure here: https://imgur.com/a/c9RXR

Homework Equations


Fc = FT
Fc = 4π2mr/T2

The Attempt at a Solution


I assume that there are more forces acting on m1 than m2. Although unsure if tension can act on both sides of an object in the same direction.
 
Last edited by a moderator:
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Greenlime770 said:
I assume that there are more forces acting on m1 than m2.
Yes.

Although unsure if tension can act on both sides of an object in the same direction.
No. If an object has strings attached to opposite sides of the body, the tensions cannot act in the same direction. Tension forces always "pull" on an object, so the direction of the tension force on a body is always along the string in the direction away from the body.

Make sure you carefully draw a free body diagram for each mass.
 
Greenlime770 said:
1. The problem statement, all variables, and given/known data
A block of mass m1 = 2.00kg is attached to a rope of length L1 = 0.50m, which is fixed at one end to a table. The mass moves in a horizontal circle supported by a frictionless table. A second block of mass m2 = 1.25kg is attached to the first mass by rope of length L2 = 0.75m. The mass also moves in a circle, as shown in the image. If the period of the motion is T = 15s, find the tension in each rope. (Assume all ropes are massless).

Image of Figure here: https://imgur.com/a/c9RXR

Homework Equations


Fc = FT
Fc = 4π2mr/T2

The Attempt at a Solution


I assume that there are more forces acting on m1 than m2. Although unsure if tension can act on both sides of an object in the same direction.

Additionally to what TSny suggests I would recommend to find the force(s) and period for each body separately.

EDIT: I mistakenly said period. I meant to write the resulting tension.
 
Last edited:
QuantumQuest said:
Additionally to what TSny suggests I would recommend to find the force(s) and period for each body separately.
If I were to solve for m2 and the tension of L2 do I have to take into account the mass of m1 as I would have to with L1?
 
Greenlime770 said:
If I were to solve for m2 and the tension of L2 do I have to take into account the mass of m1 as I would have to with L1?

Note that you have two rotating bodies connected with rope and this system connected to a fixed point by another piece of rope. How do the two bodies interact?
 

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