Help Stuck on these 2 problems

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The discussion focuses on solving two physics problems involving motion equations. The first problem pertains to an ideal pendulum, where the tangential restoring force is derived from the gravitational force acting on the mass, leading to the period equation T = 2π√(l/g). The second problem involves a homogenous cylinder rotating around its axis with a mass attached via a massless cord, requiring the application of rotational motion equations and torque principles. Clarification is sought regarding the setup of the second problem, specifically whether the mass is rolling towards the cylinder or rotating around it. Overall, the thread provides foundational equations and guidance for tackling these physics challenges.
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Help! Stuck on these 2 problems

1. Determine the motions equations of an ideal pendulum of mass m and lengh r.

2. A machine is formed by a homogenous cylinder of radio R and mass M. It rotates in its axel (frictionless). A mass by an inextensible cord (massless) is roller to cylinder. Find the motions equations.
 
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joselyn said:
1. Determine the motions equations of an ideal pendulum of mass m and lengh r.
This is fully explained in many texts. All you need to work out is the tangential restoring force on the pendulum mass:

F_{tang} = ma_{tang} = tangential component of mg.

2. A machine is formed by a homogenous cylinder of radio R and mass M. It rotates in its axel (frictionless). A mass by an inextensible cord (massless) is roller to cylinder. Find the motions equations.
I am not sure I understand the problem here. Is the mass on a horizontal frictionless surface begin rolled toward the cylinder or is it rotating about the cylinder?

AM
 


Hi there,

I am sorry to hear that you are stuck on these two problems. I can definitely try to help you with them.

For the first problem, to determine the motion equations of an ideal pendulum, we can use the equation for the period of a pendulum, which is T = 2π√(l/g), where T is the period, l is the length of the pendulum, and g is the acceleration due to gravity. From this equation, we can derive the equations for the position, velocity, and acceleration of the pendulum as a function of time.

For the second problem, to find the motion equations of the machine formed by a homogenous cylinder, we can use the equations for rotational motion, which are θ = ωt and ω = αt, where θ is the angular position, ω is the angular velocity, and α is the angular acceleration. We can also use the equation for torque, τ = Iα, where τ is the torque, I is the moment of inertia, and α is the angular acceleration.

I hope this helps you get started on solving these problems. Let me know if you need any further assistance. Good luck!
 
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