Mechanics- connected particles

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Discussion Overview

The discussion revolves around the mechanics of connected particles, specifically focusing on a system involving pulleys, masses, and the effects of tension and acceleration. Participants explore the kinematics of the system, including the time taken for one mass to reach a certain position and the behavior of the system when the string breaks.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Some participants state that both masses will have the same magnitude of acceleration and that the tension in the string on both sides of the pulley will be the same.
  • Equations of motion are proposed to solve for the system's acceleration, including the equations $Mg - T = Ma$ and $T - mg = ma$.
  • One participant mentions obtaining an acceleration of 2 m/s² and a speed of 1 m/s for mass p when mass q reaches the pulley, while expressing uncertainty about the time calculation for q(b).
  • Another participant indicates that when the string breaks, mass P is 1.2 m above the ground with an initial speed of 1 m/s and is in free fall, leading to a discussion about the time taken to reach the ground using the equation $\Delta y = v_{y_0} \cdot t_2 - \dfrac{1}{2}g t_2^2$.
  • There are conflicting answers regarding the time it takes for mass P to reach the ground, with one participant suggesting 0.1 s and another referencing a textbook answer of 0.9 s.
  • A later reply indicates that the problem can be solved using the quadratic formula, leading to a conclusion of 0.4 s for t2, resulting in a total time of 0.9 s.

Areas of Agreement / Disagreement

Participants express differing views on the time calculations for the system, particularly after the string breaks, with no consensus reached on the correct time values. Some calculations lead to different interpretations and results.

Contextual Notes

Participants rely on specific assumptions about the system's behavior, such as the uniformity of acceleration and the effects of gravity during free fall. There are unresolved mathematical steps and dependencies on definitions that may affect the outcomes.

Shah 72
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20210530_213825.jpg

I got the speed of p when q reaches the pulleys = 1m/s, a= 2m/s^2
Iam getting time = 0.8s for q(b)
 
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You really need to figure out how to post a readable image ...

atwood.jpg


Both masses will have the same magnitude of acceleration. The tension in the string on both sides of the pulley will be the same.

$Mg - T = Ma$

$T - mg = ma$

solve for the system for acceleration, then use your kinematics equations for uniformly accelerated motion to answer the questions.
 
Last edited by a moderator:
skeeter said:
You really need to figure out how to post a readable image ...

View attachment 11169

Both masses will have the same magnitude of acceleration. The tension in the string on both sides of the pulley will be the same.

$Mg - T = Ma$

$T - mg = ma$

solve for the system for acceleration, then use your kinematics equations for uniformly accelerated motion to answer the questions.
I got the ans for this.
 
skeeter said:
You really need to figure out how to post a readable image ...

View attachment 11169

Both masses will have the same magnitude of acceleration. The tension in the string on both sides of the pulley will be the same.

$Mg - T = Ma$

$T - mg = ma$

solve for the system for acceleration, then use your kinematics equations for uniformly accelerated motion to answer the questions.
Iam still having doubts with q(b)
For q(a)
I got a= 2m/s^2 and speed of p when q reaches the pulley = 1m/s
Q(b)Time when the system is released v= u+at1
t1=0.5s
After the string breaks, there is constant speed
I don't understand
 
skeeter said:
You really need to figure out how to post a readable image ...

View attachment 11169

Both masses will have the same magnitude of acceleration. The tension in the string on both sides of the pulley will be the same.

$Mg - T = Ma$

$T - mg = ma$

solve for the system for acceleration, then use your kinematics equations for uniformly accelerated motion to answer the questions.
20210602_182216.jpg
 
when the string breaks, P is 1.2m above the ground moving downward with initial speed of 1 m/s and is in a state of free fall.

$\Delta y = v_{y_0} \cdot t_2 - \dfrac{1}{2}g t_2^2$
 
skeeter said:
when the string breaks, P is 1.2m above the ground moving downward with initial speed of 1 m/s and is in a state of free fall.

$\Delta y = v_{y_0} \cdot t_2 - \dfrac{1}{2}g t_2^2$
The ans is 0.1s but the textbook says 0.9s
 
skeeter said:
when the string breaks, P is 1.2m above the ground moving downward with initial speed of 1 m/s and is in a state of free fall.

$\Delta y = v_{y_0} \cdot t_2 - \dfrac{1}{2}g t_2^2$
Oh I got it. It will be a quadratic equation and I solve using quadratic formula
 
skeeter said:
when the string breaks, P is 1.2m above the ground moving downward with initial speed of 1 m/s and is in a state of free fall.

$\Delta y = v_{y_0} \cdot t_2 - \dfrac{1}{2}g t_2^2$
Thank you so much. t2= 0.4s so total time will be 0.9 s
 

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