In this problem to mass bodies are kept on a smooth horizontal surface and they are tired with the help of a light string. So let's say this is the smooth horizontal surface on which two masses are kept and they are connected with the help of a string masses are given in the problem, let us say this was the body, this was the mass block A. And this is must this must block B. And this is must block A. And Masa Block A. That is M. A. Is 10-K. Z. And M B Is 20 K. Z. Now, in first we are applying 600 Newton force in two different cases. So in first case we are going to apply at the block E. So if we apply, uh we have to use this instagram one more time. So let me copy this. So it will save our time. No, the 4th f. is applied on the block a. Of magnitude 600 Newton. And we have to determine what is the 10cent force in this case. So this is the situation. A. Now, first we will draw a free body diagram for both the blocks. So if we draw a free body diagram for mass block B. So there will be a normal reaction on block. Be let us say N. B. And there will be weight of the block B. That is MB into G. That will be acting in downward direction. And there will be tens and force in their strength, which will be acting Which will be acting along the string and away from the object. So here the object is be therefore the direction of 10cent will be in the right direction. Now, if you draw the same thing for our four block A. So what are the forces acting on block? A First one will be the normal reaction that will be acting in a poor direction, and then the weight of the block that will be acting in downward direction. Tencent force will act along the string and away from the object, away from the object. It means that it should be either in left or right, but a string is on left side. Therefore the tencent force will act in left a direction. Now the friction, not the applied force is acting in down in the right direction. Now under the action of this force the entire system will move with same acceleration, so whatever be the acceleration of four Block A. The same acceleration will be for Block B. Let us say the acceleration is A. So what will be the Newton's second law of equation for both the blocks? So if you write the motion of equation for Block B. So what we can write is that net force acting in the direction of acceleration. So here the direction of acceleration is A. And the net force in the direction of acceleration is only tencent force. So 10cent force will be equals two massive blog be into acceleration of blog. So from Newton's second law of what we can write is that net forces equals to mass into exploration here. Net forces. Tencent force. And most of the block is M. B. Into A. It is. See this is equation one. Similarly, if you write equation of motion for the block A. So what we can write is that net force acting in the direction of acceleration is equals to mass into acceleration. So the direction of acceleration is the positive direction. So here forces acting in forward direction, intention is acting in backward direction. So what will be the force or net force? So net force will be yeah minus T. So what we can write F dynasty that is net forces equals to mass of A. Into acceleration of A. So from here we can replace the known quantities. So what we can replace tencent with the help of a question one. So we can write F minus MB into a will be equals two M. A into A. Therefore physicals too, M E into A plus MB into A. We can take a common from the right hand side. So F will be equals two M E plus MB into A. So what will the value of actual reason? So actual reason will be forced divided by some of the masses. That is M. A. Plus MB. Now forces given in the problem which is 600 Newton and masses are 10 KZ and 20 KZ. So the actual reason comes out to be 600 divided by 30 m per second squared, which is 20 m or second describe. So, this is the value of actual reasons. Now we can put the value of actual reason in equation one. So putting equals to 20 yeah meters per second squared an equation one. So what will be the value of tencent? Tencent will be must be. So, what is the must be? It was 20 K Z. Multiplied by actual reason. That is 20 m per second squared. So tense and force becomes 400 newton. So this will be the value of 10cent force in case that is when the forces applied on must block A. Now we have to apply the same must block the same force, but on mass Block B. So in second case we have to use the same diagram, but this time force is applied on mass Block B. All right. So again, we will draw a free body diagram for both the blocks. So, if we go to drop for the Block B, so there will be a normal reaction that the ground will exit on the block. Be. Let us say the forces N. B. And there will be a weight of the block That will be acting in downward direction. So MB in 2G, the force external force will be acting in the left direction, and the Tencent forces acting in the right direction, not for a. The normal force will be acting in a poor direction. Mass or the weight of the block will be acting in downward direction. Tencent horse will be acting in the left direction. Now, let us see that under this, under the action of the external force. The entire system accelerates in left direction with acceleration A. So each block will have the same acceleration A. In the left direction. So what we can write is that both of these are accelerating in the left direction with same axel's recent. Now we can write equation of motion if we write the equation of motion first for block A. So what is the net force acting on the block? A. Net force is in the direction of acceleration. That will be T. That is equals to mass of A. Into X. Terrorism, Let us say this is the equation three. Now, what we can write equation of motion for the block B. So for block B the net force will be so the force F. Is acting in the direction of actual reasons. So F will be positive and tencent forces acting in the opposite direction of actual reason. So we will write minus t. Remember here we are not we are not considering or we are not are dealing with the vertical forces. Why? Because these forces will balance each other. There will be no motion in vertical direction. So N. B. Will be equal to and being too easy. But these values are not required for the calculations. So I'm not going to write those equations. I'm only writing those equations which are going to help us to find the value of acceleration and then to find the value of tension since the tension is acting in horizontal direction and acceleration of the objects are in horizontal direction. Therefore we are only concerned with the horizontal forces and accelerations. Okay so what is the net force acting on the blog? That is F dynasty that will be caused to massive blog. Be into actual reason. Now we can replace the value of tencent tea with the help of equation three. So what we can write F minus M. A. into a should be equals two MB into A. Now we can send this Emma into eight them to the right hand side. So F. We'll B equals two M. A. Into a less. And being to A. So F will be close to if we take common acceleration. So A into M E. Less MB. Now if we divide both sides of the equation with me plus MB. So what will be the acceleration? So it will be F upon M. A. Plus MB. So what is F F. 600? Newton and Emmy As 10 and MBS 20 K. Z. So this is equal to 20 m per second squared. Again, we see that the acceleration remains seem that is 20 m per second described. Now if you put the value of acceleration in equation three, so putting Equals to 20 m/s described in Equation three, What will be the value of 10cent? Tencent will be me, which was 10 and two 20 Newton, so this will become 200 Newton. Therefore, in this case, 10cent forces 200 new dinner. So this is the answer. Fun, Part B of the problem. Okay.