u/DitiIsCool

I'm trying to determine whether a video filmed inside a theater has the sound of a "crowd cheering" edited in. This is the spectrogram.

This was recorded in 2010. It was likely recorded on a camcorder.

I also downloaded the spectrogram of a video that is actually recorded in a movie theater and has the real cheer of a crowd.

This was recorded in 2021. Probably on an iPhone.

Can I confirm the the first spectrogram has the noise of a crowd edited in?

For the first picture, my understanding is that the directions I chose are invalid because the negative accelerations mean that Block B is actually moving to the right instead of the left, and Block A is moving down instead of up. That means, for Block B, my friction force will be in the opposite direction I chose, and the T2 should have the belt friction multiplier instead of T1. If I oppose my directions and redo my free-body diagrams, then I will get the answers that are in the solution manual.

For the second picture, according to my professor's solution manual, the work on top (above the horizontal line) is correct. My professor defined A and B as going down, and C going up. He solves and gets negative accelerations for both. I thought that meant you have to redefine your directions and redo your free-body diagrams since your friction will be pointing in the wrong direction. However, my professor doesn't do this, and just plugs in the negative accelerations he calculated. On the bottom (below the horizontal line), I tried doing the problem with the correct directions, and I got negative tensions.

My question is if there is a sanity check to know which calculations are correct. I wasn't getting negative tensions for the first one, so how do I know what is correct? I already plan on asking my professor. I was just curious to see what is said here. Thanks.

It was a video of this guy giving money to a homeless man, and they think he's going to go buy a bunch of liquor, but he gets a bunch of a food for a homeless family. This is all recorded from a distance. It might've been a Joey Salads video, or someone of the like.