Taking my dynamics exam in an hour, been watching these videos all day to cram and be prepared. Your explanations are super helpful, and I like that you pause at parts that could potentially be confusing and go over it in different terms. It is incredibly helpful, thank you for all your hard work! I'm sure you're helping hundreds if not thousands of other students with these videos. Thank you!

This is the best explanation of this topic, I've binged watch all of your dynamics videos! Loving it. The clearest explanation in the whole youtube!

This is my first ever youtube comment. You have an excellent channel. Explanations are clear and straight to the point. You provide great animations as well as solving each exercise and step clearly. Thank you for your great work, keep going!

Extraordinary video on conservation of energy and dynamic great effort from the man all hail his hard work knowledge has no limits hatts off to you may your channel reach 1 million subscribers very soon your destination and destiny both are defined in this video keep working hard on it never give up⚡⚡⚡⚡

This entire playlist is so helpful, thank you!

Thanks for the great video. To be honest, I actually have the most difficulty in the work done by non-conservative forces portion of this topic. T1 + P1 + integral(F_nc *dr) = T2 + P2. I believe adding this topic could help greatly. Thanks again for the great playlist

Thank you so much. It is crystal clear now!

Thank you for the amazing work! Keep it up! I have one question I'm a little bit confused on and would appreciate greatly if you can clear it up for me, please. For the last problem, I get that the final gravitational potential energy for Block A is positive because it is above our chosen datum, and vice versa for Block B. But is there any reason why in the change in displacement equation you have deltaS_A=(deltaS_B)/3 instead of -(deltaS_B)/3 when solving for deltaS_A? Would we change the sign to positive anyway when plugging it into conservation of energy equation? I'm confused on that part.

I'm so grateful I found this channel. Love you bro💙

Thanks again! I have a question by the last example though. If we assume the system has no potential energy in the beginning, how then can it start to move by itself?

Sir you are great, and the way you teach is outstanding. Love from Pakistan

Hi there :) for the second example, why are the potential energies of the springs positive? I think maybe I am confusing this with the previous video's concepts, but would the potential energy not be negative as it is opposing the motion of the block? Many thanks x

I once more come for your help. I have 3 days left before my Dynamics exam which consists of the following hibbeler topics: - chpt 12 (done) - chpt 13 (done) - chpt 14 (done) - chpt 15 - chpt 16 - chpt 17 - chpt 18 - chpt 19 - chpt 22 So far I have only covered the first three chapters (12, 13, 14) so I have about 6 more chapters to go. Based on your experience of all these chapters what do you recommend is the best way to prepare for my exam in the limited time of 3.5 days I have left? Like do you recommend for example watching all these videos (which are very good!) and just doing some preliminary and fundamental exercises? Or do you think there's a better way to prepare/study these chapters? Or are there any chapters which you think aren't as important as others? Do you recommend going fast through certain chapters and spending more time on the tough ones? Since you have covered most of these topics I thought maybe you could tell me what is the best way to prepare for these 6 chapters in a short amount of time. Any advice is greatly appreciated!

Great video. On the spring example why is the work done by spring positive and not negative when the box is dropped?

Hi Mr. Steven. well appreciated for your effort. I need to point out something. In 7:55 I don't get why you did consider the s as 0.2 when you write the gravitational potential energy because I see that two springs compress for 0.2 m which makes 0.4 m when we add them up. So don't we need to write 0.4 m for the gravitational potential energy?

In the first problem, I saw you use TB + VB = TC + VC to find the velocity C in which you got 13.1 or 14(which I got) I Used TA + VA = TC + VC to solve the problem which resulted in the same answer. However, think you have a point that we may run into problems similar to that in which TA + VA = TC + VC may not always be a guarantee.

OMG thank you, finally I understand.

Thank you so much for your videos - they are sooooo Helpful. Time marker at 9:30 - why is it not 3Sa + Sb = l +2a? you have the right-side just = to "l + a". Also how did you get the original equation to start with?

Thanks for making these videos! I have a question about the first problem at 7:26 I understand that we need to recalculate the Normal force at B because our velocity at C is higher than the minimum required at loop C, but why is it that we use the radius at loop C for finding the normal force at B?

Nice explanation 👌

Thanks this video is very useful

Sorry I have so many questions video but for the spring position equation why did you include 2(Sa-a)? I’m still rusty on these pulley problems do you have any recommendations to really get the concept of when you count some sections vs when not? I’m practicing to no avail. 9:40

1:06 would the force of a bendy spring be conservative? how about a spring that doesn't have the same k throughout?

The second problem, I notice that you have T2 the Final Kinetic Energy as 0. I thought it starts at rest at the dadum and as it falls it should have some speed before it lands on the spring. Why would final kinetic energy be 0.

Awesome,best way to clear our concepts with the video problems

9:02 Are we allowed to separate the energy equation into two equations: one for mass A and one for mass B? Or we could only use one since it is a complete system? Thanks for the reply.

Thank you Sir. May Lord bless you always.

very very heplful thank you so much keep it up

Hello, I have to say that I truly appreciate the effort that you have put into your videos. However, upon further inspection, is it perhaps the case that you did not cover section 14.4 "Power and Efficiency"? Regardless, these videos have been invaluable for my learning, thank you.

Hi at 8:57, how did you get 286.7? I followed the same calculation and I got 268.7. Great video by the way. They are super helpful!!

Awesome videos on Dynamics, will definitely recommend to other students.

keep it up keep it up keep it up, you are the best!

hi, can you clarify when to use principle of work and Energy, conservation of energy, linear impulse, conservation of momentum and angular impulse? like what kinds of situations required certain equations?

why does SA not equal to negative 1/3 of SB (10:00 part of the video)

At 4:49 why is N and W both positive? Shouldn't they both be negative for pointing downwards?

i would like to ask question number 2 . Do we consider the kinetic energy to be zero when it hit the spring, because when the block hits the spring the velocity automatically would be zero?

7:32 how would you find normal force at B?

hello, can I ask regarding to the question number 2. I don't understand why potential energy for A and B is positive ? hope you can answer my question. Thank you :)

wait sir so according to what i learnt last year is that the Mechanical energy is only conserved if the are only conservative forces and in the last example you used the principle to solve s_b while the was the tension in the pulley which is non conservative

When do you use this method instead of the Principle of Work and Energy?

In the third problem, should the (delta-Sb)/3 be negative because when you move Plus Delta-Sb to the other side it should be negative. Why is it positive.

Nice video

Why is the N-force at 4:15 zero?

Why the normal force at B = 0?

4:37 why is the Normal force =0?

thank you this was helpful

Thank you very much

• Some inside understandings from this video : 1) Conservative force is the force in some potential field which stores the kinetic energy of body in potential energy due to to position from reference datum. For eg. Gravitational force for body w.r.t. earth's surface, Spring force for a spring due to its elastic deformation w.r.t. mean configuration. 2) Work done by conservative force is path independent i.e. we can take any path or trace any distance between any planar two points in conservative force field with same work. 3) Frictional force is no conservative because, it degrades or consumes the kinetic energy to lower forms i.e. heat which is non-mechanical energy. Hence, work done by frictional force is path dependent. 4) In absence of friction in the path of motion, there is complete conservation of mechanical energy. Hence, both kinetic & potential energies are completely inter-convertible. 5) Larger is the path of motion, larger will be the loss of mechanical energy due to friction which is path dependent & directly absorbs at every local displacement along the path. 6) For bodies in motion in space or plane, there are inherent forces like friction & fluid drag (depends on relative air velocity) which consumes/absorbs the mechanical energy to rise local temperature of both bodies or fluid interfaced surface in contact. Here, total energy is conserved but mechanical energy is not.

When I think of conservative forces, I would think of objects, bodies, affects apply the same amount of force on each other. For instance, let say I was applying a force on the wall. In order for the wall to stay still, it would have to apply the same amount of force on me. If I was applying a force on a spring, than in order to come to a complete stop at that instant position, it must apply the same amount of force on me. This is, I think, where Newton Third Law comes in. It says for every action, there is an equal and opposite reactions. Let alone I also notice that the force that applied on me, whether is on a spring or due to gravity, would have to go same distance as previously in order to return back to it’s zero point.

TYSM :))

in the second question I thought gravitational potential energy going down is always positive work done ? why is it minus in this case

thx u bhai

you make this stuff look like a cakewalk

10:38 shouldn't it be negative delta S/3?

Why is Normal force equals 0 in the first question?

in the previous videos, u mentioned that spring compression will make negative work because the slow down the motion(on the conservative part) why do not we apply this concept to this problem

wish me luck tomorrow is my engineering dynamics final

Why is the normal force 0 at the top of the loop?

For the first one, i dont understand why Nc wouldnt also be zero since it is following same rules as B “right before it leaves”

why N=0 should not be = mg ??

🐐🐐

Love your videos, but I have a suggestion for you to change the name of your channel to something like: Pure Concept Learn the How or something to the same as it. just an opinion

Shi hai

Nice