 Let's solve a couple of questions on the properties of distance and displacement. The first one says Sarthak is driving a car on a straight road. The car's displacement in a certain time period is delta x i.e. minus 1 km. Which of these could be correct about the distance covered by the car during the same time period? And we have to choose all the answers that apply, which means there could be more than one correct answer. All right, as always, pause the video, give this one a try first. Hopefully you have given this a shot. Now it says that Sarthak is driving on a car on a straight road and the car's displacement is minus 1 km. So let's try to draw this. Let's try to draw, let's try to draw a car and the car, okay, this is all right. So here we have the same car and this is the same car and the displacement, displacement, this is, this is delta x that is given to be as minus 1 km. If we try to represent the car as point object, we can say that the initial position is over here and the final position is here and delta x, this is again the displacement is minus 1 km. This is the initial position IP and this is the final position FB. And this displacement, minus 1 km, this displacement really tells us, it really tells us the shortest distance. It tells us the shortest, I'm just trying to choose a pen over here, okay, tries to tell us the shortest, shortest distance between any two points. So between these two points, the shortest distance is minus 1 km. So distance really cannot be less than 1, right? Because, because of displacement is the shortest distance between these two. How can the distance be less than, less than 1? Over here, minus sign is just telling us the direction. So if the, so here we have assumed that the left direction is negative. So it's, it's displaced by 1 km to the left. That's the minus sign, it tells the direction. And 1 is the shortest distance between these two points. So option A is wrong, distance covered cannot be less than 1. Option B says, distance covered is more than 1 km. So for this one, let's think about a scenario. Let's say the car started from this point and then went all the way, like followed this path, went a little back, then again came forward, then went much ahead in the final position, then came back to the final position. Even in this case, the displacement is still minus 1 km, because the displacement only depends on the initial and the final position. It does not depend on the path, the entire journey, all the distance that the car traveled. So here, yes, the distance covered is more than 1, it's insanely more than 1 km, but the displacement is still minus 1. So option B, the question is which of these could be correct? Option B can be correct because distance traveled can be more than 1 km. Distance covered is 1 km. Well, let's see if the car started from the initial position and then it just went straight and to the final position. Here, the magnitude of displacement is 1 and also the distance covered is 1 km. So distance covered can be equal to the displacement and this is only true if the car traveled in a straight line, in a straight line between the initial position and the final position. The car traveled in a straight line without ever reversing, going back or going far ahead in the final position. It started from initial position and then straight line traveled to the final position. Only then the distance can be equal to the displacement. All right, let's move on to the next question. Here we have Manveer who observes a car's motion on the road and draws the distance L versus time T curve for the car as shown below. Here is a curve. Farouk looks at the curve and immediately concludes that this curve is drawn incorrectly. So Farouk says there is something wrong with this curve. Which portion of the curve led Farouk to this conclusion? Again, as always pause it, try it once on your own and then resume the video. Okay, so we need to choose one answer A, B, C, C, D. Which portion of the curve could be wrong? So now let's think about it. Manveer is observing a car's motion on the road and draws the distance L versus time and Farouk looks at it says something wrong. So this is a distance versus time curve. L here is distance. So okay, the car starts from A and as time progresses it travels some distance reaches point B. Nothing really seems wrong with that. Car is traveling forward. Now after point B, the curve it bends down and this is where the point C is. Let's try to draw that as well. This is point A and this is point B. So this happened in the first in this much time interval. Let's call it T1. So this much happened in T1. And then after point B it is at point C. So in this portion of the curve it means that a distance is decreasing with time. Distance is decreasing with time. Maybe that could happen if after point B the car went back, the car went back and now this is a point C. Maybe this is what the curve is trying to show. But we are drawing a distance versus time graph, not a displacement versus time graph. Distance cannot decrease, it cannot decrease with time because even if the car started moving backwards you are still traveling more distance. You traveled initially AB then you traveled some more BC. So distance, it will need to increase constantly because even if you reverse, if you start going back you are still traveling, you are covering more ground you are traveling more distance. Yes, if there would have been displacement versus time graph then that story would have been different. But the distance, distance can never really decrease. Even if you start going back it's still covering more ground, traveling more distance will always, it will always increase. So BC seems to be the wrong part of the curve. Let's look at CD. CD means that there is no change in distance as time progresses which can totally be true because the car could be at rest. So CD can also be right. So turns out BC is wrong. BC is the wrong portion of this curve because the distance has been shown to decrease in this part of the curve which is not possible.