Okay i hope you're able to see ladies and gentlemen so very very much important guys they want you to use the work energy theorem okay so do not use anything else other than wag energy theorem very very much important ladies and gentlemen use this theorem to calculate the work done on the object or on the soldier by fraction after moving through the height of 20 meters so ladies and gentlemen they want you to use that theorem okay to calculate the work done on the soldier by fraction this is what the question wants you to calculate.
So that means you are actually calculating a the force as a result of friction but most importantly ladies and gentlemen at all times try you know to to visualize exactly what the question wants you to calculate remember on that 5.2 we drew a labeled free body diagram okay so it's in most cases where you need to refer back to that diagram that you draw okay so ladies and gentlemen please do allow me to quickly redraw that free body diagram because it serves as a guide for us in order to be able to visualize exactly what they want us to calculate.
So this is that force by tension and we we've got a force of gravity and again we've got force by friction okay can you see ladies and gentlemen so that means these are all the forces acting on that object okay so now the question wants us to use the work energy theorem to calculate a you know the work done on the object or on the soldier by friction after moving through the height of 20 mm of 20 meters so ladies and gentlemen this is um you know one of those questions where you might need to apply a your full understanding.
Ladies and gentlemen let's just quickly try to check something um let me see use the work energy theorem to calculate the work done on the soldier by friction after moving through a height of 20 meters so what i'm actually trying to check ladies and gentlemen is to check if they want us to calculate the work or the force remember these are two different things ladies and gentlemen there is work done as a result of a particular force so this is a a a free body labeled diagram of the forces acting on that object so because of this different forces ladies and gentlemen they are making some work on that soldier okay so that means a this question actually wants us to calculate the work as a result of the fractional force not sure if you you understand ladies and gentlemen i'm not really sure if you understand
but the best way to make you guys understand is by saying our final answer should be in joules and not in Newton. I hope ladies and gentlemen this opens your eyes and you fully understand what i'm trying to say because at first i read that question as if the question wants us to calculate the force okay so it's very much important ladies and gentlemen that you you know especially when you're practicing i always say there's a value in every mistake and i try by all means to be the one making those mistakes on your behalf but most importantly please do make sure that as soon as i've done this question you go through my telegram channel to browse through all the question papers that are posted there
and then as soon as you identify a question which is similar to this one then you give it a try and make those mistakes i've got a whatsapp number where you can just a you know confirm where you've gone wrong by just sending a photo of your calculations then in that way i'll be able to notice that okay this is what a pro approach looks like this is what you're trying to do in that way i'll be able to guide you in terms of how a to go about that question the right way.
And again i'm going to try and find out which mistakes you made how you made those mistakes then we discuss those mistakes so that you are aware of the types of mistakes associated with that particular chapter in that way ladies and gentlemen if you make those mistakes at an early stage i can tell you i can promise you now that in the exam room you won't make those mistakes even if you can do those mistakes you will still be able to recover from those mistakes so ladies and gentlemen i hope you are now on the same page the question wants us to calculate the work which is measured in juice the work done on the soldier by friction after moving through a height of 20 meter ladies and gentlemen we are using the wake energy theorem okay the work energy theorem i've just explained to you that on the formula sheet you're given these formulas ladies and gentlemen.
Let me just check exactly where that formula is this is the chapter that we're dealing with work energy and power okay so ladies and gentlemen we know wake is equals to force delta x or delta y depending on whether the object is moving up and down or sideways and then cos zero and this is the formula that we're using white net is equals to a kinetic i mean change in kinetic energy and this is the formula for calculating the kinetic energy let me just write all of those formulas ladies and gentlemen so that you are able to notice and understand the relationship so let's not just make this lesson about answering that question okay remember the first formula we've had it when we're defining the theorem which is what net is equals to delta k okay and again we notice there's this formula which says wake it's equals to force multiplied by because this object is moving up up and down
ladies and gentlemen let's use a delta y if it was moving sideways we would use delta x okay so it's f delta y times a cos of angle theta okay and the other formula ladies and gentlemen is that a k or a if you don't want to say k you can say e k okay uh i'm not sure how to kill him just do a forward slash and ek it refers to the same thing which is kinetic energy it's equals to half m v squared you obviously know this formula from a i think what is it great curry 10 okay so ladies and gentlemen i just want to try and solve this question while having all of this formula so that you understand the relationship and again i'm going to quickly explain a lot with regards to those formulas so ladies and gentlemen this is where i got those formulas that given on your formula sheet you just choose a...
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