 All right friends. So here is another question that is asked by one of our students. This is Dheera's from Centrum Academy welcoming you All right. So let's read the question a Block weighing 10 Newton travels down a smooth curve track AB Join to a rough horizontal surface. Okay, the rough surface has a coefficient of friction Which is point two? If the block starts slipping on the track from a point one meter above the horizontal surface How far will it move on the rough surface? Okay. Now, let's say that the block moves At a distance X on the rough horizontal surface. Okay so we can say that let's extend this a little bit and Let's say this block Is moved horizontally till here. All right, and we call this distance to be X Fine. Now the curved surface AB is smooth, right? It is written. So There is no work done by the friction till A to B the friction is doing work only from point B onwards Up to a distance of X Right now if you look at this block, which is sliding on the horizontal surface You'll immediately make out that the friction force is acting back side and Whose value is mu times n and the value of n is equal to mg If you balance the forces vertically All right. So force of friction Will be equal to mu m g So if you substitute the values mu is point two M is The sorry m into g directly is given it is 10 Newton's right So it is 10 m into g product is 10. This will come out to be 2 Newton so friction force is 2 Newton and Mind you friction force is acting in opposite direction of displacement. So work done due to the friction force Will be equal to minus 2 into X All right because force of friction is acting opposite to the direction of displacement All right. Now, let's try to write down work energy theorem between this point point number one and Let's say where it stops point number two. So work done on this block is equal to u2 plus k2 minus u1 plus k1, right now We are not considering work done by gravity here because gravity work done is taken as Potential energy fine. So the forces for which you have considered potential energy You need not consider work done because of them So only work done remaining here is work done due to the friction because normal force also doesn't do any work as The normal force is perpendicular displacement all the time hence The total work done is a frictional force which is minus 2 times X All right and u2 is what if you take this horizontal level To be zero potential energy zero gravitation potential energy u2 is Zero Okay, and k2 is what k2 is also zero it stops. All right minus U1 is what u1 is initial potential energy, which is equal to mg into 1 meters All right, plus k1 k1 is also zero Isn't it so you'll get minus 2x is Equal to minus mg and m into g is 10 So minus 2x is minus 10 and X will come out to be equals to five meters All right, so I hope you have learned something today in case you have any doubt Please feel free to get in touch with us. Okay. Thank you