Dynamics: Lesson 25 - Work and Energy Balance Hard Example

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[collinaustin]

I'm taking dynamics right now. More videos please! They are so helpful!

[ibahesjproductions]

PLEASE CONTINUE THE DYNAMICS VIDEOS, I HAVE AN EXAM IN 4 WEEKS!

[allnimblybimbly]

For everyone wondering about the signs of PE for block a and b: The signs are for the work done by gravity. Not for actual PE. Block A moves down in the direction of gravity, hence the sign is positive. Block B however moves up against gravity, hence it's negative. It's confusing because PE increases when you move upwards (against gravity) normally. The signs are there to denote Work, not the actual PE increasing. It's a little tricky but he's doing it this way to keep from getting mixed up I think. Technically yes the PE of Block A goes down because it moves down, but the work DONE by the PE is positive. Hope that helps yall because I was lost af for a bit haha.

[adamgriffith]

"nothin sticks to Teflon... except pans" im weak

[anthonykeeler]

This is amazing. I bombed my first Dynamics test, and my second one is tomorrow. I feel so much more confident.

[alfreduanekee]

Awesome ...please Dr Hanson continue with your wonderful work ..God bless you

[Lexyvil]

I'm kind of confused on why the potential energy "after release" is 0, when potential energy relies on height (mgh formula), knowing that block "B" gained a height of 1.73 ft in the vertical direction.

[AzizHyssin]

this is my final year in engineering ...i just want to say you are the best

[thenatmann]

Thank you for this video! There are so many steps involved and you do a great job explaining everything,

[zachrosedahl]

for potential energy wouldn't the friction be static because its not yet in motion?

[tashfeenahmed]

What about the work done by tension for each block?

[r.ulquiorra]

But in 10:38 aren’t the forces in the same direction with motion? i mean if the weights is our forces and the bokes are moving in the direction due of their weight and gravity there’s no outside force so we can detect why did we put on - for both WFa and WFb im confused 🥲

[georgesadler]

DR. Jeff Hanson, thank you for solving this difficult Work and Energy Balance problem in classical Dynamics. I did not fully understand this problem from start to finish, however I will watch this video multiple times for a deep understanding and breakdown of this topic.

[NiamPatel-mf]

For work for fA and fB wouldnt it be cos30 and cos60

[bbgg]

just a question why the kinetic energy before is and why the position energy is 0 after release

[alianjohnson]

thanks so much for your informative videos. in your video you mention 'your book' - could you tell us what that book is? regards

[mrcoffee]

you didnt explained why you suddenly put the negative sign on the PE1 of block B after pausing the video

[be]

Why do you not multiply by the distance for the work done by friction

[Shawn-nlmg]

My dynamics class is passed this and has started fluids. 6 weeks to go. Do you teach a short dynamics class or something?

[eyadsalah-eddine]

I am pretty sure that since potential energy = mgh; you made a slight error. Main reason why is because you said potential energy= 60lbs*(0.1)sin(30), shouldn't it be ?