Simple harmonic motion homework

[misterpicachu]

Homework Statement

all below

Relevant Equations

all below

I don't know how to start doing this homework. I would like help to
orient myself.

 

[berkeman]

Homework Statement:: all below
Relevant Equations:: all below

View attachment 267234
I don't know how to start doing this homework. I would like help to
orient myself.

Welcome to PhysicsForums.

Per the rules, you need to start working on your homework problem before we can offer tutorial help. Try writing the energy equation that is asked for in the first part. Have you worked with pendulum problems in the past?

 

[haruspex]

If you cannot yet attempt the energy equation, start by identifying the mass centre the question refers to and adding the angle it mentions to the diagram.
Then list the forms of energy that need to be in the equation, then the variables which contribute to those.

 

[misterpicachu]

If you cannot yet attempt the energy equation, start by identifying the mass centre the question refers to and adding the angle it mentions to the diagram.
Then list the forms of energy that need to be in the equation, then the variables which contribute to those.

that's the problem in my classes we never work with pendulums only with springs

 

[haruspex]

that's the problem in my classes we never work with pendulums only with springs

I do not see how that prevents you from attempting the steps I listed. Have a go.

 

[misterpicachu]

I do not see how that prevents you from attempting the steps I listed. Have a go.

the mass centre gave me (√3/2)*L and then I used it as the height in the potential energy formula, is that ok?

 

[haruspex]

the mass centre gave me (√3/2)*L and then I used it as the height in the potential energy formula, is that ok?

Height from what baseline? And what about the angle θ?

 

[etotheipi]

For purposes of calculating the gravitational potential energy of this rigid body, you can equivalently consider a point mass $2m$ located at the centre of mass (if you are interested, this is because if $\vec{g} = -g\hat{y}$, we have $U = \int_{\mathbb{R}} d^3 x\rho(\vec{x}) g y = g\int_{\mathbb{R}} d^3 x \rho(\vec{x}) y = Mg\bar{y}$), like this:

$\theta$ is defined here as the angle of the centre of mass from the downward vertical. What is the potential energy of this configuration, up to a constant?