00:01
Hello and welcome to this video solution of numerate.
00:04
So here it's given that there are two boxes of masses 792 kgs and 888 kgs are tied to both ends via of a light vertical rope as shown in this figure.
00:14
Right.
00:16
So here we have got a and here we have got b.
00:20
Right.
00:25
And both are connected by a string.
00:31
Right.
00:32
Kind of like this.
00:33
Sorry, there is no string at the bottom.
00:36
Right.
00:36
The masses are you have got ma that is equal to 792 kgs.
00:49
You've got mb that is equal to 888 kgs.
00:53
Right.
01:00
A constant upward force f is applied to the box starting from the rest position.
01:08
The box b descends 108 meters in 6 seconds.
01:12
Right.
01:14
Now it is seen that you are applying this force f still this box b is getting down.
01:20
Right.
01:20
It's descending down.
01:21
Right.
01:22
So what you can do is you can let's say the acceleration of the system be a.
01:27
Right.
01:29
So if we just balance the force this is mb mass of b times g is acting down.
01:35
Right.
01:35
This is resisted by the tension t and the overall force mb times a is acting downwards.
01:45
Right.
01:46
Or what we have is mb a that is equal to mb g minus tension t.
01:52
Right.
01:52
So let's say this is equation 1 or it's the best is you find out t the t value of t will be equal to mb g minus mb a.
02:03
Right.
02:03
Let's say this is equation 1.
02:07
Right.
02:07
Next for the upper block the tension is sort of acting like this.
02:13
Now the same tension and the weight ma g is acting down and the overall force ma a is acting downwards.
02:25
Right.
02:26
So here you will be having ma a that is equal to t plus ma g minus f minus f.
02:38
Right.
02:38
So this is what we have...