00:01
Hello friends, we are having a problem in which a piece of metal is heated to temperature theta and then allowed to cool in a room which is at temperature theta not the graph between temperature of the metal and time t will be closest to which one? so let us see all the graph first so that we can answer this problem easily first of all if i draw these two coordinate axis and then again two coordinate axis for third and fourth options then they will look like this now there is a graph with here and that graph is between temperature t and time t.
00:34
Now again i can write temperature t and time t.
00:37
And here also it will be temperature t and time t.
00:39
And again here it will be temperature t and time t.
00:42
Now what happens is that i can just, you know, write the answers as like this.
00:48
Sorry, if i just draw the graph like this, then they will have some values or some figures like this.
00:55
Then there will again be a graph over here like this.
00:58
And then what i can do is that i can just you know draw it like this because it looks like this right so the third graph looks like okay so i have to use another dotted line or you can say another line and in this line the graph is like here from here to here it is like this and then again there is one more line from this point which looks like this now the fourth option okay have i drawn all the options so this is my exactly fourth option and then here is one more graph so if i point out all the you know if i name these graphs it will be a it will be b and this one is c and this one is d i hope everything is clear as such till now now if you want me to you know i have some dotted line over head then i can draw it like this by using eraser so they will look like this i hope there is no problem as such with these videos okay with these structures.
01:57
So what will happen? i can just write here that out of these graphs in order to establish a relation, what i can do, i can just, you know, i can just solve it further as using the equation of newton's cooling law.
02:13
So from newton's cooling law, i can write that d -theta over d -t is directly proportional to theta -0.
02:21
Then here, theta is temperature of the body and theta not is the room temperature...