Kinematics Problem Solving - Physics Solutions

[ramadhankd]

Homework Statement

The homework statement/question is in my post.

Relevant Equations

So does the equations and attempted solutions. I just wanna ask whether or not my solution is correct, because the question has a triangle symbol on It, and It supposed to be complex. Solving It that easily gives me anxiety. Please kindly help.
Thanks.

 

[BvU]

Seems to me you describe some equilibrium situation. What would $\theta(t)$ look like ?

[edit] And I don't see when $a=g$ would normally ever happen (unless the wire breaks ).

 

[ramadhankd]

It's actually a dynamic question. The question is on the top left in my post (problem 3/92). We need to find the value of maximum theta. In my opinion, this condition will be reached when the pendulum have no relative motion with the slider, thus having the same acceleration a = g. I just wonder if this condition I set for max theta is right. Also, I use polar coordinate approach to analyze the kinematics while in the end, It doesn't matter at all because I only need to project a into r and theta component of acceleration (the value of r, and other defining properties of a polar system doesn't matter). Is this right?

 

[BvU]

I should have read the small print ...

So the equilibrium $\theta$ is $\pi/4$ and the pendulum swings around that angle. Any way to describe the motion ? With the initial condition $\theta = 0$ the answer seems easy.

I think your condition for $\theta_\text{max}$ is correct - but it leads to two solutions.

 

[ramadhankd]

For the motion description, I think that the motion is that the pendulum has the constant acceleration a when θ=θmax. As for the two solutions, what are those? I'm sorry for the late reply, I've been out this weekend.

 

[BvU]

You don't list any equations to determine the motion. 'I think' doesn't help.