00:01
Hello everyone, in this problem we are given that a tank contains 80 kg of salt and 2000 liters of water and it is given that the solution is of the concentration of 0 .02 kg of salt per liter enters a tank at the rate of 6 liter per minute.
00:29
So in the first part of the question, we need to find the concentration of our solution in the tank initially.
00:35
So, initial concentration is of 80 divided by 2000 on dividing this we have the value to be 0 .04 kg per liter.
01:05
So that is 80 kg of salt in 2000 liter of water was there in the tank initially.
01:14
Now let us move on to the next part of the problem where we need to set up an initial value problem for the quantity of y in kg of salt in the tank at the time t minutes.
01:27
So here let the amount of salt be y.
01:45
So then y dash to be equal to rate in minus rate out.
01:53
So here the rate in is 6 multiplied by 0 .02 and rate out is 6y divided by 2000.
02:02
So here the solution enters and leaves at the same rate of 6 liters per minute.
02:09
So now simplifying this we have this value to be 0 .12 minus 6y divided by 2000.
02:20
So simplifying this we have the value of dy by dt to be equal to 0 .12 minus 6y divided by 2000.
02:32
So from this we get dy multiplied by 1 divided by 6x minus 240 to be equal to 1 divided by 2000 dt.
02:46
On integrating both sides we get log of 6y minus sorry here is also y.
02:58
So log of 6y minus 240 to be equal to minus 60 divided by 2000 plus log of c.
03:10
So from this we get the value of y of t to be equal to 40 plus 1 by 6 c e power minus 6 by 2000.
03:23
So this is the required initial solution and here the initial value is of y of 0 to be equal to 80.
03:36
Now substituting this here as in the given so it would be 80 substituting value of t to be equal to 0.
03:45
So we have 80 to be equal to 40 plus c by 6...