Acceleration of Falling Mass Attached to 5cm Pulley

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SUMMARY

The discussion centers on calculating the acceleration of a falling mass attached to a pulley with a radius of 5 cm. The user initially attempts to apply tension formulas (Mg - T = Ma) but finds incorrect results. The correct approach involves using the kinematic equation Y = Yo + (1/2)at², which accounts for the uniform acceleration over a specified time interval. The moment of inertia of the pulley must be considered when applying Newton's second law, but in this case, kinematics provides a straightforward solution.

PREREQUISITES
  • Understanding of kinematic equations, specifically Y = Yo + (1/2)at²
  • Basic knowledge of Newton's second law and tension in systems
  • Familiarity with the concept of moment of inertia
  • Ability to analyze motion in a pulley system
NEXT STEPS
  • Study the application of kinematic equations in different motion scenarios
  • Learn about the moment of inertia and its impact on rotational dynamics
  • Explore advanced tension analysis in pulley systems
  • Investigate the relationship between mass, acceleration, and force in various contexts
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in understanding the dynamics of pulley systems and the application of kinematic equations in real-world scenarios.

hannibal
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I have a question where there's two masses attached to a pully that has a radius of 5 cm. one mass is heavier than the other one and the first part of the question is asking you to find the acceleration of the mass that's falling (it falls 75 cm in 5 sec). Now the way that i figured it should be done is by using the tension formulas (Mg - T = Ma for the mass falling) however this give the wrong answer, the equation you have to use is Y = Yo +(1/2)at^2. I can;t seem to figure out why you can't use the first method to figure this one out.
 
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hannibal said:
I have a question where there's two masses attached to a pully that has a radius of 5 cm. one mass is heavier than the other one and the first part of the question is asking you to find the acceleration of the mass that's falling (it falls 75 cm in 5 sec). Now the way that i figured it should be done is by using the tension formulas (Mg - T = Ma for the mass falling) however this give the wrong answer, the equation you have to use is Y = Yo +(1/2)at^2. I can;t seem to figure out why you can't use the first method to figure this one out.

To use Newton's second law for such a problem you would have to consider the moment of inertia of the pulley. However, since the acceleration is uniform and you are given the time interval and the displacement, you can just use plain old kinematics \Delta s = at^2/2 and solve for a.
 
Ok I know what the moment of inertia is, however my phys prof had to skip over the last chapter in the book due to time constraints. If there was no moment of inertia then the tension/force method would work right?
 

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