I've binged all of your kinematic videos, after feeling lost in physics 11 for ages. I can't thank you enough. I feel like it's starting to make a little more sense now.
You probably dont care at all but does someone know of a way to get back into an instagram account? I stupidly lost my password. I love any tips you can offer me
Honestly, you will save my academic life - I'm doing Biomechanics this semester and in week one, my head is spinning! How do you know so much Professor Dave?!
if you find the acceleration/deceleration confusing, you're not alone. A lot of education places only use acceleration and the direction is indicated by positive or negative. They do this to avoid confusion and even though people are used to the colloquial "deceleration" once you get used to the idea of "there is only acceleration" and the direction is indicated by positive or negative, it can make it a lot easier to keep the directions straight in your head.
I am confused of why they halved acceleration when looking for the origin of x. I might need to consider changing my perspective of acceleration to understand.
Your explanation of understanding motion using a graph (grid) to show the starting and ending positions in order to observe the changing (+- or -) of the vector's displacement, velocity and acceleration now allows me to understand physics of motion. I hope to now pursue basic calculus.
You should be in charge of a government agency somewhere and/or someday. This is sort of kind of like the re-beginning of an Italian Renaissance. It comprises the acculumation of and review of all ascertained scientific fundamentals, put in a more visible and comprehensive form. Added details is the success to these videos.
Thank you very much for the amazing explanation! But may someone explain why for stage c and d(reverse acceleration and reverse deceleration) For D (Displacement Vector) the direction is Forward instead of backward? Because I thought you are going back to the original starting point that's why should be backward instead? Thank you
sir i have a doubt, if a horse pulls a cart by a certain force then according to newton 2nd law cart should also pull him with same force so how does a cart move.
Thank you thankyou thankyouuhh very muchh, I have a final physics exam tomorrow and u explained me a whole chapter thankuu you’re literally saving my life
I have a question. In the answers of the check your comprehension, the answer for reverse deceleration and reverse acceleration states that the Displacement is moving forward and the magnitude is decreasing. Shouldn't the displacement be moving backwards, and the magnitude decreasing too? Since we're reversing back towards our starting location, I thought the displacement's vector would be backwards to where its original starting point was.
so don't forget that displacement will always begin from your starting point, so the only way for it to become negative is for you to go past where you started and begin traveling in the opposite direction from there. so it's not that displacement is moving forward, it's just that it's always pointing forward, until you get back to your starting point, where displacement is zero.
@@ProfessorDaveExplains In reverse acceleration and reverse deacceleration displacement is in forward and velocity is in backward directions How can it be? The direction of velocity will be in the direction of displacement isn't it?
@@ydhanusree4126 because by 'displacement' here he meant 'overall displacement (ie.from displacement from the starting position). So if you look at the position of body even during reverse acceleration/deceleration, the position (ie. the overall displacement) of the body is forward to the starting point. Though the instantenous displacemnt will be in the backward direction therefor the instantenous velocity is also in the backward direction. The catch here is that here according to Prof Displacement = Overall displacement; Velocity = Instantenous Velocity I guess he should've been just a bit more clear about that. Nevertheless a sweet and simple way of explaining by him.
I have this written in my book, can someone explain it to me. "when brakes are applied then the direction of velocity and acceleration are opposite to each other"
well so if you are moving in the forward direction you have a positive velocity, and if you hit the brakes the acceleration will be in the negative direction, so until you stop completely you'll have a decreasing but positive velocity and a negative acceleration, opposite directions.
Why do you look all happy and friendly during the theme song, and then completely serious and without a smile at all during the explanation?!? I thought you liked explaining this stuff?
Hi Professor 😊 I’d like to ask, for the Checking Comprehension part, how is the acceleration for Initial Decelaration “backward” and for reverse deceleration “forward”? Kindly enlighten me, Sir. Thank you so much and apologies for the inconvenience. 😊
Reverse deccelaration means the car has changed its initial direction means Velocity vector become backward and as we have to deccelarate it accelration vector become forward(so that velocity vector in forward direction opposes velocity vector in backward direction)
Reverse acceleration has a forward direction displacement does not make much sense. So does this mean the direction of the object itself is the direction of the arrow, not the direction of the velocity? 6:58
During reverse acceleration why does the displacement vector point forward, shouldn't it point backwards instead since the car is moving in reverse direction
This was a great video but it did kind of leave me asking myself what displacement actually is. For those also confused it's the position in reference to the origin, so if I travel 4 meters to the right from the bus stop and one meter to the left, the distance traveled would be 5 meters but the displacement would be three meters to the right since that is where you are relative the bus stop (regardless of how you got there).
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Because displacement is a measure of how far the car has moved in a particular direction, in this case forwards. As the car reverses, its forward displacement from its original position gradually decreases until it is back where it started. If it continued reversing from here, then the direction would change to backwards.
Vivid explanations ,I really admire that ,you are good at it ,....but would you give explanation for the comprehension part specially I am having trouble in the determination of the direction of the quantities displacement ,velocity and acceleration in some cases .
There isn't enough information to know for sure that acceleration is constant, in the given problem. To keep it simple, introductory kinematics assumes constant acceleration unless otherwise specified.
Sir, i have a wrong perception with respective direction. Please help me to correct in required places If displacement is shortest distance between two(A,B) points, it will have single direction A to B And Velocity is displacement/time velocity should have single direction. Why it is given as velocity can change by changing direction or speed or both.
since displacement is the shortest distance from one point to another (always a straight line), it'll always be in a single direction, so velocity is also in one direction in that case. It is still velocity because it is still moving in some direction. But velocity is a vector quantity, which means it has direction and spee
Give me the formula of "a certain force accelerates a 3.6kg mass by 1.4m/s². what would be the acceleration of 2.2kg mass when the same force acts on it
Idk if you'll see this but this is how so the equation f=ma will help (it is in si units so kg and meters/s² and the result is in newtons) so 3.6×1.4=5.04 newtons now we use this force and work backwars get the force then divide it by the second mass so 5.04n÷2.2kg= ~ 2.2727272727m/s² hope this helps
Because the displacement in the problem is measured relative to your original starting point, rather than relative to the starting point of the interval. You never touch the negative x-positions in this example, so your displacement is never negative.
Sir, I have a doubt - 1. In the cases of reverse acceleration and reverse deceleration, why does the displacement points in forward direction.. 2. Also, by modifying the data given in the (checking Comprehension) question, please state me some instances in which the magnitude of the acceleration of the car will increase or decrease.. Thanks...
Well, I'm not professor Dave, but 1. The displacement points forward because the car is always technically located in front of its starting position, and not behind it. 2. The acceleration (change in velocity) does not increase or decrease because it doesn't in real life (or at least I think so)
@@petarblag I think that the acceleration is constant bcs the change in velocity is constant Say that the velocity of the car during the first five seconds increases from 0m/s to 10m/s. In the next 5 seconds it increases to 15m/s but then in the next 5 it increases to 35 m/s So in this case the acceleration is not constant. For the first 5 sec its 2m/s² In the next 5 sec its 1m/s² and in the 5 sec after that it's 4m/s² So I think if the velocity increases or decreases inconsistently so will the acceleration
Nice video and explanations. Thanks . Still not clear: What is the difference between distance and displacement? BTW, thanks for clarifying velocity and speed.
so like if you walked ten meters forward and then ten meters backwards to where you started from, you would have travelled a distance of twenty meters, but your displacement would be zero, as you're back in the same spot.
Depends on whether you just mean magnitude of acceleration, or acceleration in its full vector form. Because it is only when acceleration is perpendicular to velocity, that it exclusively causes a change in direction of velocity. This is called centripetal acceleration. One example of a constant acceleration vector, is projectile motion in a uniform gravitational field. Throw a ball in a direction that is perfectly horizontal. Initially, the acceleration is perpendicular to the velocity, and only causes a change in direction. But once you let the effects of that acceleration accumulate, the ball starts descending, and the velocity is no longer perfectly horizontal. Due to the fact that part of velocity now aligns with the acceleration, acceleration causes a change in speed in addition to a change in direction. There is only an instantaneous point, where the acceleration is purely centripetal, without also being tangential. In uniform circular motion, the acceleration is constant in magnitude, and so is the speed. But both the acceleration and speed have to change direction constantly, so that acceleration is always perpendicular to velocity. These two kinematics quantities remain constant in magnitude, but not constant in direction. Because they are vector quantities, it is incorrect to call them constant if direction is changing.