Mixing Salt and Water with Changing Volume

This is a sequel to my video "Mixing Salt and Water - First Order Differential Equations". Please review this tutorial first. Link: • Mixing Salt and Water ...
This video demonstrates modelling of a mixing problem with changing (unsteady) reservoir volume.
Thanks for watching. Please give me a "thumbs up" if you have found this video helpful.
Check out my playlist on Differential Equations: • Calculus: Differential...
Graph at the end of the video created with Desmos Graphing Calculator: www.desmos.com...
Please ask me a maths question by commenting below and I will try to help you in future videos.
I would really appreciate any small donation which will help me to help more math students of the world. Please donate here: paypal.me/Mast...
Follow me on Twitter! MasterWuMath

[@akusen9]

very nice breakdown!

[@MasterWuMathematics]

Glad you liked it!

[@MohammadDeaibes]

so where did the (0.2t^2)/2 for the next part because instead of 9000 for c i got 4500

[@jessypintoguzman9120]

Merci! Very helpful!

[@MasterWuMathematics]

You’re welcome!

[@afiqhaiqal3706]

hello again sir.. i want to ask, if the volume of substance in tank is decreasing, should the volume equation become V-initial minus with cahnge of volume? is it correct?

[@MasterWuMathematics]

Hi! Happy New Year. In short yes. But it doesn't matter if you chose your sign to be a Plus because your net flow rate will be negative, and a plus and a minus still gives you a minus.

[@afiqhaiqal3706]

@@MasterWuMathematics woah.. tq tq 👍🏽👍🏽😂 sorry sir for disturbing.. sending love from Malaysia

[@0.Abdulrahmannn]

Sorry sir but why is the initial salt quantity wasn't used?

[@JohnJohn-xn7sp]

the y(0) is the 15, so once he plugged the 0 in, c/600=15 is the equation solved to get c.

[@ghreqerhoah138]

Sorry Im a little hung up on where that +y went in 7:21 it just disappeared

[@MasterWuMathematics]

No it didn't just disappear, it got absorbed into the derivative on the left hand side of the equation after we multiplied through by the integrating factor. I have not done a video on integrating factors as of yet, but it's coming. It may pay to review this material.