I don't get the acceleration relation in this ex

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Homework Help Overview

The problem involves analyzing the relationship between the accelerations of two particles connected by a pulley system, with specific parameters including masses and friction coefficients. The original poster seeks to understand why the acceleration of one particle is related to the other in a specific way.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the implications of the pulley system on the accelerations of the two masses, questioning how movement and acceleration of one mass affects the other. They explore the relationship between distance moved by each mass and the resulting accelerations.

Discussion Status

Participants are actively engaging with the problem, raising questions about the mechanics of the pulley system and the relationship between the movements of the two masses. Some have offered insights into the reasoning behind the acceleration relationship, while others are seeking further clarification on the mathematical aspects.

Contextual Notes

There is a noted confusion regarding the movement of the masses in relation to the pulley, with participants reflecting on the implications of the rope's behavior as the masses move. The original poster has expressed uncertainty about the mathematical explanation for the observed relationships.

Lenjaku
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Homework Statement


find the relationship between the 2 particles' accelerations.


Homework Equations


m1=20kg
m2=40kg
wheel doesn't weigh but can move.

both particles move with friction.

μs=μk=0.2

F(t)=98e0.1t

The Attempt at a Solution



I came up with 3 equations:
F(t)-fk1-T1=m1a1
T1=2T2
T2-fk2=m2a2

Why is the acceleration equation
a2=2a1?
 

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Lenjaku said:
Why is the acceleration equation
a2=2a1?

Due to the pulley.

If M1 moves 1 meter to the right how far does M2 move?

If M1 moves at a velocity of 1m/s to the right how fast does M2 move?

If M1 accelerates at 1m/s^2 to the right how fast does M2 accelerate?
 
The pulley is attached to m1. So they have to have the same acceleration when the rope between them is under tension. If the pulley moves 1 meter, then 1 meter of the m1 rope has moved on both sides of the pulley, so 2 meter of rope has gone past the pulley, so m2 moves twice as much as m1.
 
There is no mathematic explanation then? :( .Since the rope near the wall 'lengthens' the same value it 'shortens' near m2 while m1 keeps on going does it mean that m1 moves twice the distance m2 moves?If so it makes sense for me :S

edit:
I just noticed I mean m1 moves less than m2, m2 moves twice the distance >.<
 
Last edited:

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