Linear Impulse and Momentum (learn to solve any problem)

Learn to solve problems that involve linear impulse and momentum. See animated examples that are solved step by step.
If you found these videos helpful and you really want to give something, it's very much appreciated.
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What is impulse and momentum? (00:00)
The 50-kg crate is pulled by the constant force P. (01:16)
The 200-kg crate rests on the ground for which the coefficients (03:40)
The crate B and cylinder A have a mass of 200 kg and 75 kg (06:00)
Find more at www.questionsolutions.com
Book used: R. C. Hibbeler and K. B. Yap, Mechanics for engineers - dynamics. Singapore: Pearson Education, 2014.

[@yamanghazi]

this is the best dynamics tutorials i have seen I like your style, don't change anything, just please make videos about every single subject, you are doing a very good job, I think you are the best at this.

[@QuestionSolutions]

Thanks so much for your comment, I really appreciate it. Best of luck with your studies!

[@muratbayraktar4114]

I think this channel needs to be discovered by the KZbin algorithm. So underrated..

[@QuestionSolutions]

Many thanks, I appreciate it!

[@birajmalakar7349]

Strongly agree

[@juliotitosagastegui9453]

i have 3hrs for my dynamics exam, and this videos will do the trick they have saved me before (with a 90) and they will save me now. thanks, your tutorials are amazing, pretty straight forward

[@QuestionSolutions]

I'm super happy to hear these videos help. I wish you the best with your dynamics exam. Keep up the awesome work 👍

[@whatsyourname1825]

I usually don't post comments, but about two months ago I commented on your page a few days before my midterm exam. In fact, I didn't do as well as I expected. Our doctor put an exercise I barely understood what was written on the exam paper, but I swear if I hadn't watched your videos, I would have handed my paper empty of any answer. As for now, my final exam is Monday, I have a lot of hope that I will get a high score because of you. Also I am in the hardest engineering college in my country, many days I cry but I am lucky that you saved my academic year

[@QuestionSolutions]

First, I am sorry to hear your midterm didn't go as well as you'd expected. Sometimes, exams can throw curve balls, but I hope you do amazingly on it. Do your best, don't give up, and keep up the good work. :) Thank you for taking the time to comment.

[@Oscar-gx2yf]

Your videos are the most straightforward and concise on the subject! I have learned a lot from all your videos of dynamics. Thank you for these!

[@QuestionSolutions]

I am glad yo hear they have been helpful. You are very welcome and I wish you the best!

[@RK-tx5xb]

Great way explained for solving Impulse and momentum questions. Best part I like where F, V & T was focused for this chapter. Keep on posting great video.

[@QuestionSolutions]

Thanks for taking the time to comment, much appreciated. :)

[@ephe8949]

I love the animations. They really help.

[@QuestionSolutions]

Glad to hear that! Best wishes with your studies.

[@surgeace444]

Thank you so much! Now i fully understand this concept!

[@QuestionSolutions]

Glad to hear! Best of luck with your studies.

[@alexbarretogranada4633]

Great explanation thanks so much!

[@QuestionSolutions]

You're very welcome!

[@DavidMOUSSONGA]

You make it too easy sir , thank you!🙏

[@QuestionSolutions]

You're very welcome :)

[@Mac-ih7rb]

idk who is disliking all of these videos, most likely a hater, but I've found your dynamics series super helpful. I'm taking it over the summer so it's all crunched into 4 weeks.

[@QuestionSolutions]

Haha, I don't think there are any videos with just likes and no dislikes, just part of how it is I think :) Thank you so much, I really appreciate your comment. Best of luck with your dynamics course.

[@maxss7163]

Very helpful 👌 Thanks man

[@QuestionSolutions]

Glad it helped :)

[@austincb90]

Outstanding, thank you for sharing

[@QuestionSolutions]

You're very welcome!

[@SAM-ux3km]

Amazing sir you are a legend, I am currently studying dynamics from the book "RC Hibbler" and your videos helped me a lot, great animations and style of explaination.

[@QuestionSolutions]

Glad to hear it helped! Thank you for your wonderful comment, best of luck with your studies!

[@swaaggy]

best lectures and examples

[@QuestionSolutions]

Many thanks!

[@madhankumar8463]

you are GOLD !

[@QuestionSolutions]

Many thanks!

[@riss8858]

life makes sense when i am watching your videos...

[@QuestionSolutions]

😊 That's good! I hope they are very helpful to you.

[@sindbadthesailor4808]

Nice animations!

[@QuestionSolutions]

Thanks so much and I am glad you like them!

[@farzan_fit9]

This channels deserve millions subs

[@QuestionSolutions]

Thank you so much!

[@laneca223]

Great video as always!! Please consider doing fluid mechanics as it is one of the toughest class and I'm taking it next semester :((((((

[@QuestionSolutions]

It's on my list to do :)

[@zero___point]

@@QuestionSolutions o 😂

[@MdJunayed]

Who are you? And why are you so underrated?

[@QuestionSolutions]

I am sure time will tell 😅

[@ashenravindu2480]

Thank you very much

[@QuestionSolutions]

You're very welcome!

[@maryamakram7153]

Amazing...

[@QuestionSolutions]

Thank you very much! I appreciate it. :)

[@user-uk1ge6go5k]

Thank you Sir. May Lord bless you.

[@QuestionSolutions]

Thank you very much!

[@DzahierulAliemy]

thank you sir

[@QuestionSolutions]

You're very welcome!

[@hermionegranger9742]

thank u so much

[@QuestionSolutions]

You're very welcome!

[@Johnny-nd2wl]

Thanks 😊

[@QuestionSolutions]

You're welcome 😊

[@mutasem1335]

Hi Many thanks for these vidios in the last example you said that the velocity direction for the crate will be up. you are right but logically it should be down because the weight of crate is more than the cylinder. 7:53

[@QuestionSolutions]

Pulleys act like levers, so sometimes, it can be confusing to see which way an object moves, regardless of their weight. It's like lifting something very heavy with your fingers by using a very long lever arm. We can only assume a direction and follow along until we get contrary info to change our assumption.

[@chadbullard979]

@@QuestionSolutions Thank you, was thinking the pulleys were responsible too, but lever arm is a great analogy. I was not sure how to think about how the pulleys reduced the weight. Great analogy.

[@SublineYT]

At 3:05, why do you multiply by the normal force for the horizontal impulse equation? I thought it's only acting vertically up.

[@QuestionSolutions]

The 0.2(N)(5) part? That's the friction, which is horizontal. Friction is normal force multiplied by the coefficient of friction.

[@joshuacharlery5826]

Nice video

[@QuestionSolutions]

Thanks!

[@yosef_syr751]

Thanks ❤

[@QuestionSolutions]

You're very welcome!

[@FlopIsTheName]

My god.... I shouldve found you 3 weeks earlier, I've been cursing at my professor for his lack of proper explanations

[@QuestionSolutions]

😅 Best of luck with your studies

[@saniyyahsepanik4659]

Thank you for your tutorials. Why at time 2:10 in this problem "N" is not = to "mg"?

[@QuestionSolutions]

N is not always "mg", that's only true for very basic questions. Weight is always "mg." In fact, in this question, we see that N was equal to 387 N, which is not equal to "mg." Normal force is dependent on other forces, in this case, there is force P applied at a 30 degree angle. That means the y-component of force P will effect the normal force. I hope that helps :)

[@nisargpatel9315]

Does direction of positive have to be same as direction of your reference lengths from datum for the equation mv1 + sum of impulses = mv2?

[@QuestionSolutions]

Which question are you referring to? Or in general? It's a lot easier to keep everything positive by initially picking a direction and keeping it that way. Less confusion and you can easily find mistakes that way.

[@nisargpatel9315]

@@QuestionSolutions last question with the crate and cylinder

[@QuestionSolutions]

@@nisargpatel9315 Yes, try to keep everything the same positive direction you use for the reference lengths (the position coordinates for the pulleys). So if the position coordinates were downwards, then that's your positive direction. It makes the math easier to keep track of.

[@andrewtrinh270]

What concept did you use in example 3 for SA + 4 SB = L and VA + 4VB = 0?

[@QuestionSolutions]

Please see: kzbin.info/www/bejne/f6bHgYN9frtoh68

[@flee3695]

sir in the 3rd example, why cant we just simply take tensions like this for the cylinder 75(9.81)=T for the crate 4T=200(9.81)

[@QuestionSolutions]

They don't really work like that. Even with your 2 equations, you get 2 different values for T when it's a single cable, the tension should be the same throughout. 😅 If you have time, please take a look at this video: kzbin.info/www/bejne/f6bHgYN9frtoh68 It's fundamental to solving most pulley problems.

[@runejanssens7681]

Is it necessary with the law of momentum to look at the direction of the velocity? I mean why why dont you need to put a minus before the velocity of the crate? Since it is moving towards the positive direction. Or do you just need to take the absolute value just as with the law of energy?

[@QuestionSolutions]

When you write your equations, you assign a direction to be positive. If you look at 3:08, you will set that we picked right to be positive. This is true for not just momentum problems, but for forces, velocities, etc. If the vector you drew faces right and you picked right to be positive, then you write the equation with it being positive. If it faces the left, you write it as negative (so as long as you picked right to be positive). At the end, if you get a negative value, that means it's opposite to your assumption, but the magnitude of your answer is correct.

[@mohammadpijoy6727]

Hi, sir i have question, how to we determine when to use equation of equilibrium or use the equation of motion to solving the problem especially for problem no. 2. thanksss

[@QuestionSolutions]

Equations of equilibrium are used whenever something is stationary. So if your object is at rest, isn't moving, staying still or you want to figure out when it's about to move, you use equations of equilibrium, because all we are saying is that all the forces added together must equal 0 for it to stay still. Equations of motion is whenever an object is moving. 👍

[@marksamuel9132]

For example 2 why is the lower bound of integration 1.504 for the towing force. I know this is when it started moving but the towing force still acted on the box before it began to move?

[@QuestionSolutions]

So the question is asking us for a velocity. Imagine you have a heavy box in front of you. You push with one hand and it doesn't move. Does it matter to the velocity of the box the fact that you've been pushing on the box with one hand? You're pushing, so you're applying a force, but nothing is happening. It's the same here, sure, there is a towing force applied, but it doesn't matter to us, until the box starts to move. The lower bound is the time the box starts to move, that's when velocity becomes > 0.

[@marksamuel9132]

ah that makes a lot of sense thank you

[@josegregosilao414]

Hello sir! Can I ask if there's a manual solution for solving the 3rd example? I am having a hard time solving for 3 equations with 3 unknowns.

[@QuestionSolutions]

Yes, I would use substitution. Isolate for one variable, plug that into the second equation. Then isolate for the same variable and plug that into the 3rd equation. Then you can get your values 👍

[@josegregosilao414]

@@QuestionSolutions thank you kind sir! I would pay you back someday!

[@QuestionSolutions]

@@josegregosilao414 you're very welcome 🙂

[@Inspirezone__]

Pls how do we know when to use a particular concept for the question given

[@QuestionSolutions]

That's really up to you. Most questions can be solved using multiple methods. When you do more questions, you'll have the intuition to know which equations to use to get the answer fastest.

[@darksigh9196]

I tried question 3 where I assumed the cylinder going upwards (giving it negative velocity) but yield different results . Should I always assume that the cylinder is moving down?

[@QuestionSolutions]

No, it doesn't work like that for pulley problems. Once you draw your datum and pick the direction of your position coordinates, you have to stick to it. You can't change it for just one. Please see: kzbin.info/www/bejne/f6bHgYN9frtoh68

[@e-nes4042]

hocam, Can we solve question at 5.55 from t1 + u1-2 = t2 ?

[@QuestionSolutions]

Did you try it? Let me know, usually, you can solve these questions using different methods.

[@rawadhasan9111]

For example 2, why is the lower bound of the integral 1.504 and not 0?

[@QuestionSolutions]

Because that's the amount of time it took for the box to start moving. I start to explain it at 4:49.

[@lucascoghe3427]

In the third problem I tried to solve it using F=ma for the cylinder and crate and then substitute a in v(3)=0+a*3 but my answer is not the same like yours. Why can't I use my method?

[@QuestionSolutions]

It's hard to say without seeing your steps. Are you trying to use f=ma without using impulse?

[@lucascoghe3427]

@@QuestionSolutions Yes! without impulse just by drawing a free body diagram for the cylinder and crate and using the third equation from the pulley for acceleration. Is it possible I can't use the equations for constant acceleration?

[@clearflow7925]

4:42 why isn't friction positive if anything away from the datum is positive

[@QuestionSolutions]

You should watch this video first, which specifically talks about pulleys (kzbin.info/www/bejne/f6bHgYN9frtoh68). Datums apply to pulleys, not the rest of the forces. Hope that helps.

[@AzharKhan-cy5kt]

I didn't understood the 2nd numerical after applying formula for x axis ...can you please make videos more clerifying

[@QuestionSolutions]

Please kindly provide a timestamp so I know where to look. Many thanks!

[@obensorelkose1718]

In the first example, why did he put Normal Force (N) as a variable but didn't just do mass x 9.81 instead?

[@QuestionSolutions]

Your concept about the normal force is incorrect. It's not just mass times 9.81, it's only that if there are no other forces effecting it and it's only a flat surface. If you look at the value we got for the normal force, it's not 50x9.81. Make sure to go over how a normal force works because you'll end up messing up problems and I don't want you to fall into that pitfall.

[@AhmedMahmoud-gu4un]

I would pay for this but don't get any ideas. Thank you

[@QuestionSolutions]

The content is here for free, for any student to learn. 👍

[@ribyjamer3927]

How to solve the last example in calculator??

[@QuestionSolutions]

Which part of the last question?

[@ribyjamer3927]

@@QuestionSolutions the 3 unknowns

[@QuestionSolutions]

@@ribyjamer3927 I don't know if your calculator can do it, most calculators can do up to 3 at the same time. If not, you would have to use substitution or use something like wolfram alpha.

[@ribyjamer3927]

@@QuestionSolutions okay. Thank you so much 🥰

[@QuestionSolutions]

@@ribyjamer3927 You're very welcome. Check your calculator manual, it'll tell you how to solve up to 3 simultaneous equations (if it's supported).

[@Eva-ld9hh]

2:30

[@QuestionSolutions]

Do you have a question? 😅

[@Eva-ld9hh]

@@QuestionSolutions no😊I am just marking my spot in the video, thank you for the helpful content

[@QuestionSolutions]

@@Eva-ld9hh Ahh, okay! You're very welcome.

[@yiust]

For question 3, can I first solve for tension using F=ma 75g - T = 75a 200g - 4T = -200a Before using T to solve for velocity through momentum and impulse equation.

[@QuestionSolutions]

You can basically solve these problems in many ways to get the same answer. I only showcase a single method. So if your way gets you the same answer, go for it :)

[@turkiye6186]

Nice video but you need to add TURKISH subtitles

[@QuestionSolutions]

If you know Turkish, please add the subtitles, or if you can send a subtitle file with the subtitles and the time stamps, I can add it in as well. Thanks!

[@khalilalnajri9988]

We need the explanation to be translated into Arabic

[@QuestionSolutions]

I don't speak Arabic but If someone can type it out in Arabic with timestamps, I can add the subtitles for you :)

[@hidden280]

where is the turkish commentary, I have dynamic final exam. Be fast

[@QuestionSolutions]

I don't speak turkish. You should find a turkish person who creates videos on these topics.