00:02
Hi, so we have a question in which the situation is given like this.
00:06
We have a block b.
00:11
It is kept on a table where the coefficient of static friction is mu is equal to 0 .25.
00:23
Okay, a string is attached to this block.
00:29
It is a horizontal string.
00:33
There is a knot and this string falls down.
00:39
Another block a is attached to the string and at the knot there is another string which is attached to the vertical wall this angle the string this string makes with the horizontal is theta equal to 30 degree okay we are given the weight of block b w b which we are given is equal to 711 newton.
01:20
What we need to find is there.
01:22
We need to find the weight of block a.
01:26
We need to find w .a.
01:30
This is our question.
01:32
So let's consider block b first.
01:36
We will draw the free body diagram of block b.
01:52
Its weight is acting downwards.
01:54
Weight wb is acting downwards.
01:57
Normal force on it is being acted up.
02:01
Since it is in vertical equilibrium therefore n is equal to wb okay also the coefficient of the tension will on the block b will be in this direction so the tension will be along this direction since we are being told to find the maximum weight of w a size that this this entire system is in equilibrium so the block should not move as the tension act is in the right direction on this block a frictional force is static frictional force should exit should be exerted on it in the left direction since the block is in equilibrium therefore the tension force should be equal to the frictional force initially what we had is n is equal to wb which is equal to 711 newton okay this is the vertical equilibrium case and along the horizontal what we have let's call this t1 because we will be having other tensions also let's call this t1 t1 is equal to f okay because the block is not moaning block is not moined it is in equilibrium in the horizontal direction also f you know frictional force is mu into n.
03:40
Mu here is given to be 0 .25 and n is 711.
03:47
This is equal to 177 .75.
03:52
This is our t1.
03:54
You need to remember this.
03:56
Okay.
04:01
Now let's consider block a.
04:07
Since block a also needs to be in equilibrium.
04:11
You can see that in horizontal direction, there is no force acting on block a.
04:16
The only force is acting on it are in vertical direction.
04:20
Its weight, w .a will act downwards and the tension force will act on it in the upward direction.
04:29
T -2 will act on it in the upward direction, t2...