Block-pulley system and rotational dynamics

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Homework Help Overview

The discussion revolves around a block-pulley system involving two masses, m1 = 1.0 kg and m2 = 2.0 kg, connected by a string over a pulley with a specified radius and moment of inertia. Participants are exploring how to determine the acceleration of the system in relation to gravitational acceleration.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants discuss applying Newton's Second Law to analyze the forces acting on the blocks and the tensions in the string. There are attempts to set up equations based on the forces and torques involved, with some participants questioning the definitions of the variables and the setup of the equations.

Discussion Status

There is an ongoing exploration of the relationships between the tensions, masses, and the resulting acceleration. Some participants have provided guidance on how to express the tensions in terms of the masses and gravitational force, while others are clarifying the roles of the variables involved.

Contextual Notes

Participants are working under the constraints of the problem as presented, with specific values for mass, radius, and moment of inertia. There is a focus on ensuring that the equations accurately reflect the physical setup of the system.

Kennedy
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Homework Statement


Two blocks, m1 = 1.0 kg and m2 = 2.0 kg are connected by a light string as shown in the figure. If the radius of the pulley is 1.0 m and its moment of inertia is of the system is 5.0 kg*m^2, the acceleration of the system is (expressed as a fraction of gravitational acceleration g):

Homework Equations


I believe that Newton's Second Law is the only relevant equation (F = ma).

The Attempt at a Solution


I have the acceleration to be in the direction of m2, because that's the heavier block. So, the m2g - T1 = m2a. Solving for T1 that leads to m2g - m2a = T1. On the other side of the pulley we have T2 - m1g = m1a. Solving for T2, we get T2 = m1a + m1g. Now the pulley, T2(radius) - T1(radius) = τ. We know that τ = Iα, and α = a/r.

Now, (m1a +m1g)(r) - (m2g -m2a)(r) = 5(a/r)

How do I solve this in terms of g?
 
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Kennedy said:

Homework Statement


Two blocks, m1 = 1.0 kg and m2 = 2.0 kg are connected by a light string as shown in the figure. If the radius of the pulley is 1.0 m and its moment of inertia is of the system is 5.0 kg*m^2, the acceleration of the system is (expressed as a fraction of gravitational acceleration g):

Homework Equations


I believe that Newton's Second Law is the only relevant equation (F = ma).

The Attempt at a Solution


I have the acceleration to be in the direction of m2, because that's the heavier block. So, the m2g - T1 = m2a. Solving for T1 that leads to m2g - m2a = T1. On the other side of the pulley we have T2 - m1g = m1a. Solving for T2, we get T2 = m1a + m1g. Now the pulley, T2(radius) - T1(radius) = τ. We know that τ = Iα, and α = a/r.

Now, (m1a +m1g)(r) - (m2g -m2a)(r) = 5(a/r)

How do I solve this in terms of g?
Which mass is m1 and which is m2? tension produce by m1 is t1? Then write equation accordingly
 
Abhishek kumar said:
Which mass is m1 and which is m2? tension produce by m1 is t1? Then write equation accordingly
The tension in the string attached to m1 is T1, and the tension in the string attached to m2 is T2.
 
Kennedy said:
The tension in the string attached to m1 is T1, and the tension in the string attached to m2 is T2.
m1 is the 1 kg mass, and m2 is the 2 kg mass
 
Kennedy said:
The tension in the string attached to m1 is T1, and the tension in the string attached to m2 is T2.
Kennedy said:
The tension in the string attached to m1 is T1, and the tension in the string attached to m2 is T2.
Kennedy said:
m1 is the 1 kg mass, and m2 is the 2 kg mass
Ok then t1-m1g=m1a(say equation 1)
m2g-t2=m2a(say equation 2)
and for rotational motion
t2-t1=Ia/r^2(say equation 3)
Then put the value t1 and t2 from equation 1and 2 in equation 3 you will get the acceleration
 
Kennedy said:
, (m1a +m1g)(r) - (m2g -m2a)(r) = 5(a/r)

How do I solve this in terms of g
I do not see any difficulty. Just collect all the a terms on one side and all the g terms on the other. You have the values for r amd the masses.
 

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