Đồ thị lực đàn hồi hay và khó - Thầy Vũ Ngọc Anh

The following sentence is the derivative of the magnitude of the momentum according to the delta M What is the delta M? It is said that the mass of a spring is M0, the hardness is K In turn, we add the masses of the delta M to the initial M0 Corresponding to the mass of the delta M, we stimulate it to move at the same frequency The figure on the left is the derivative of the magnitude of the momentum according to the delta M We need to find the value of F on the figure The value of F is very basic The value of delta M is 20 grams We multiply it by 4.3 times I will set the first formula Remember that it is stimulated with the same frequency I will set the formula for the momentum of the spring The momentum of the spring has a magnitude of K K times delta L0 plus A You see in these 3 quantities, which quantity is changed? That is delta L0 K and A are the numbers, the formula is fixed Just change the delta L0 Our delta L0 is Mg divided by K But with this M changed This M will add the delta M This M will be equal to M0 plus delta M With delta M, it can be equal to 20, 40, 60, 80, 100, 120 So we will give 2 points on the derivative With delta M equal to 20 And delta M is equal to 120 Right? Is that ok? Then I will set the formula for you The force at the position 120 corresponds to 5 ohms At the position 20 corresponds to 3 ohms So it is multiplied by 5 times F1 divided by F2 Equal to 5 divided by 3 Done? K divided by K Right? It will be delta L01 plus A This is 01 Divide by delta L02 plus A Done? From here we will derive this formula Right? Because this is the only condition of the equation Condition number 1 Only I will change a little I will change this 5 times Change it Delta L02 See? Plus 2A Why 2A? Because we have to subtract 3A Right? 3 times delta L01 Right? Up to now I, like many of you Think that There is only one equation But then I asked that guy Because our force will be equal to 0.8 times Right? Of F1 Right? 4 ohms 5 ohms Right? Many of you will think that it is not enough to do But actually it is beneficial Here I will derive all of them Right? Our task is to calculate F1 Right? Now we have to calculate this equation There is only one condition We have to put it here to derive Right? 5 times Delta L0 is mg over K M0 plus 0.02 Times g is 10 divided by K Do you understand why it is like this? Because delta L02 Corresponds to our weight Delta M by 20 grams It is 0.02 Right? Plus 2A Equals 3 times Delta L01 Right? Is M There But now M is M0 plus 0.12 Right? Divide by K Mg over K Done yet? Mg is 10 Right? Mg is 10 There This point is difficult to change Right? So this is 5 times 10 Equals 50 50 Right? M0 Plus 0.02 Done yet? 50 OK 2Ka So take it out here 2Ka It's starting to get a little bit neater Right? This is 30 Times M0 Plus 0.12 30 times 0.12 Done yet? OK Give me the computer Now From here you just change the equation You have added a equation between Ka And what else? Ka and M0 Alright Put the equation here To make it easier to see I will have 50M0 with 30M0 Only 20M0 left Right? Next 50 minus 0.02 Minus 30 minus 0.12 Done yet? Is 2.6 So minus 2.6 Plus 2Ka By 0 2Ka By 0 And I will draw the last beautiful line Is 10 times M0 Right? Plus Ka By 1.3 Done This is a very basic step From here, calculate F1 F1 can be Ka Minus Delta L01 Plus A Right? Just like this But when you look at it, it's not enough Ka Delta L01 is here It's already there Right? M0 Plus 0.12 Minus G Divide by Ka Delta L0 is always M and G divide by Ka Done yet? Plus Ka Right? KK divide by G G is 10 I will get 10 times M0 Plus 1.2 Plus Ka Right? So you can see I got 10M0 plus Ka It's already 1.3 Add 1.2 It's 2.5 F1 is 2.5 Newton Meanwhile, our F is 4.5 of F1 4.5 times 2.5 Right? It's 2N Right? 2N Right? And I asked you to choose the closest answer to 2N So it's a pretty basic question Actually, if you are pretty good, you will be able to calculate from here From the factor of Delta L01 is 0.2 To this one But I will do it step by step It may take a little time But it will give you a sense of self-explanatory Explain to me the question Yes, why is there a factor that can be calculated like that? Right? So I forced you to change it And if you are good at math From this From this to this Then this one This is your level And this is the most common way for many of you to follow Yes?