Kinematics Part 4: Practice Problems and Strategy

[@5uperDetective]

bruh you taught me kinematics in about 40 minutes worth of videos... compared to 3 weeks worth of lecture that I was still iffy about. You should really be in the classroom man. Educators need to stop overcomplicating these concepts and teach them like you.

[@craigkhumalo6854]

thats so true lol

[@russellerocido7897]

teachers are meant to reach a certain time quota for teaching which is kind of the reason why they drag stuff on when they teach which makes it complicated. not their fault really. but Dave is really on another level

[@shawshaneremollo3315]

I also learn kinematics from him in 1 hour compare to a 3 weeks worth of lecture

[@wislanenoel2955]

Also he seems like he enjoys teaching. Our profs are a bunch of researchers they force to teach they have no passion for education.

[@yourmom-oy7ds]

Facts

[@zahidimuhammadnasrulhaq8678]

thank you dave , i was crying all these time because i failed my examination since i didnt understand a thing . but your videos make everything clear for me. i wish you have a really nice life out there :)

[@akshayreddyatchi1971]

failure

[@netad7771]

@@akshayreddyatchi1971 Why are you so sad in your life you have to spread your sadness to others??

[@lordth7200]

@Akshay Reddy Atchi this is why your dad left you.

[@sanajindal9644]

lmao same but i still dont rly get it😭😭

[@thomasaskew1985]

I haven't solved problems like this since 1970. That was 9th grade Science for me. You covered in minutes what took me weeks to learn as a 13-year-old.

[@JohnDoe-ht2tu]

Dave, if I could send all my tuition money to you I would do it in an instant. You're so much better at teaching than any "professor" with a PhD.

[@Occ881]

Send a little bit,it's not necessarily your tuition fee

[@TheRolvaag]

You are excellent at explaining concepts in a simple manner, thank you for putting these out

[@akshayreddyatchi1971]

not at all he uses complex thing why in the world will he use v sub i instead of u. Cuz he is a professor

[@Alex-ns6hj]

@@akshayreddyatchi1971 what would u represent? why u? v_i is the same as v_0, it just denotes your initial velocity... the only u I know has a good representation for is u-sub for integrals lol

[@aronabraham4657]

Whoever came up with the invention of recorders is a genius. I don't have to tune in to classes at school as much cuz I have an online textbook, a few different youtube channels (that's only youtube), and like a few other resources for a single hw assignment. I know everyone has access to this but just wanted to say thanks formally.

[@EREN-he9jl]

wassap

[@lokeshchandore7027]

I love the intro song and animation

[@zakiyatdjabakatie7071]

lol me too

[@landofmyth221]

Same 😂💕

[@landofmyth221]

I say that intro song all day at home 😂

[@VndNvwYvvSvv]

It makes me cringe and I skip it so people don't think I'm watching videos for elementary school, because I know they won't listen to the organic stereochemistry or physics. Lol

[@UnrealogyTutorials]

He do be knowing a lot about the science stuff tho

[@birasatdahal8181]

One of the best lecturer of all time, I am quite impressed by the way he teaches

[@stefanusmutileni664]

Writing engineering physics tomorrow and confidence is rocket high cause of this video... 😊

[@Occ881]

You graduated huh?

[@stefanusmutileni664]

Yes 😅 omg I remember this comment!!! 🤣

[@gadeeecasty9073]

Congrats!

[@abdoulazizdabo9064]

You really a gift to the world. Thanks professor

[@helloAM2]

The visual aids and seeing things in actual motion really help. Shout out to the graphics team.

[@elliejohnson2786]

In case anyone missed it, and it wasn't explicitely obvious - The care package/helicopter example includes a piece of information that may not be immediately obvious. When the care package is dropped, it maintains the velocity of the helicopter, and so will have the same velocity of the helicopter. This is one of those things that isn't actually explicitely told to you, but that you can figure out rather quickly.

[@nathanhynes8063]

thanks professor Dave! Ive bought the text book for my physics unit and re watched my lecture twice. Now i finally understand after watching your videos

[@hidetsuguhiraki2008]

You know what teachers should teach her/his students. You are a great teacher, Sir.

[@castlesinfo6049]

learning calculus makes this a lot more intuitive.

[@louistwo2151]

bro when i was a senior people looked at me like a God because i perfect the exams. cant thank u enough, man. currently taking civil engineering in college now.

[@Reena-maheshwari.803]

I am a proffesional expert at NASA Agency. I always used to show your videos to my children. Me and my team trying to solve SpaceX kinematics problems to make a future Speedy (Light of speed) Satellite to find more about Universe.

[@user-fh2rw9zh8g]

Hey love your videos! Just a note for the comprehension question. Actually if we have to calculate the time in air we should be given that the ground (x'x) is still there till end. Because if he was on a hill for example then the t total isn't equal to 2tmax

[@zakiyatdjabakatie7071]

Also thank you, I understood a lot to the point that I am actually able to question answers that seem off. Thank you, Sir.

[@akshatjindal1508]

When solving projectile questions, I was confused about time in horizontal and vertical component. But after reference from your video, got everything clear

[@helviitana]

Thank you professor Dave!! 😊😊 Bless you

[@landofmyth221]

Came here from my other KZbin account to click that like button once more for 1k 😍🎉

[@mariasalvenia35]

2:37 why is x = 1.28m?

[@Obliviousovertimer17]

if only the test questions were this simple, i would have scored full

[@Spark3r]

Hey dave, really enjoyed the video and was helpful but its good to note that usually we do vy and vx in physics to tell the difference between the velocity vectors. it helps a little bit, if you ever update this video it would be nice to clarify that next time for easier use.

[@annieli3258]

This has helped me so much! I don't have to go to class feeling like an idiot anymore

[@justgocoolla]

yall know this guy is good when there are no ads in his videos

[@anthonyrichard1365]

Thank you very much, Professor Dave!

[@mekbebseyfu9371]

you're the best professor i have ever seen

[@chongyeeyun4899]

Video is interesting and creative with many easy picture and word

[@randallpetroelje3913]

Believe you and me- I also had to make calculations about water balloons, paper airplanes, and fireworks.😂👍lots of fun and no blown off fingers. Thanks again for your show.

[@fanticer]

Your lectures are superb💕💕💐💕

[@rohitsurwase5284]

Totally clear concept video .

[@saturdayBees]

❤❤❤❤❤❤❤ This is the best .. thank you sooooo much..

[@MetalAngelOfficial]

Thank you sir

[@cameronketola250]

At 4:35 how did you get 4.95

[@Horologica]

He used the quadratic equation to find T -120 = 0t + 0.5 (-9.8)t^2 0.5(-9.8)t^2 + 0t + 120

[@wakuwaku3190]

it took me this far to understand projectile motion. THANK YOU SIR! ❤

[@DaaliElizabethh]

Keep it up.thanks

[@DimuthuYapa]

Thank you, sir.

[@kujirakan9537]

this video is the best of the best

[@noraunisyafiyaabdulhalim4701]

Simple and easy to understand

[@davidrohanadorna8792]

GUFSA Given Unknown Formula Substitution or Solution Answer

[@akashpoudel571]

So nice professor dave... Hats off

[@scenify3758]

great video dave!

[@justinbeiberdrew1145]

good explanation.....

[@nikbirkundi5223]

“I love you”

[@MG22991]

Thank you so much for this video.🙂

[@amandeepbaghiana4510]

1:08 The equations aren't labeled correctly. the first equation "Vt" is supposed to be Vf (velocity final) and in the second; "Xt" is supposed to be Xf (position final)

[@ProfessorDaveExplains]

Same thing. The t in subscript means at some designated time t.

[@madibrown84]

bout to tackle my very first AP physics test. wish me luck !

[@nancyxi]

What did you get?

[@nancyxi]

Good luck if you're taking more..:)

[@shawqial-zewar6215]

thank you... ❤

[@imwmt]

Thank you

[@noooby1324]

thank you so much

[@mariasalvenia35]

thank God! I now know what equation to use

[@navenaramachendran8997]

Good explanation

[@nickdicerbo6361]

Hi Dave, it possible to find the max height using this equation: Vy^2= Voy^2 -2g(Y-Yo) where Vy=0 to solve for (Y-Yo). Vy=vertical velocity (0m/s) Voy= intial vertical velocity (~17.67m/s) g= vertical acceleration (9.8m/s^2) Y-Yo= vertical displacement (solved to be 15.94m) Then plug the value of (Y-Yo) into this equation and solve for time: Y-Yo= -.5gt^2+Voyt to solve for t and multiply by 2 t=time (solved to be 1.77s and 1.8s) To solve for t, i used the quadratic equation but got 2 similar answers. the first being 1.83 and the second as 1.77. Why did i get 2 possible answers that were so similar to eachother (and to the correct value)? Or is this the incorrect way to solve for t?

[@ericard4165]

at 3:33, i think u shouldn’t double 0.51s to get 1.02s. I think we should do that in two different part. First we calculate time for reaching maximum height, we indeed get 0.51s . But now, the velocity is 0, and the ball only due to gravity, so we just consider this as you throw this ball from cliff of 1.28m height and see how soon will it hit the ground. So 0m=1.28m+1/2(-9.8m/s^2)t^2 then we easily get t^2=1.96 we take root from both, we get 1.96s, so the first 0.51s plus 1.96s is 2.47s instead 1.02s I don’t know if I am right, this is my own opinion

[@ProfessorDaveExplains]

you certainly can do that, it's just more work. the time it takes to go up is the same as the time it will take to go down, so it's just a shortcut.

[@adi01244]

congrats, you've got π subscribers!!

[@shoosz7644]

Hey Dave please use miles as well as kilometers. Thanks.

[@ProfessorDaveExplains]

scientists only use the metric system!

[@alex_ramjiawan]

Couldn't you do the second problem using ∆y = v₀t + ½at?

[@tejsukumaran4905]

you're the goat professor dave

[@Chillwave.o]

This is it thank you

[@CaptainObvious0000]

easily doable without explicitly using formulae as well. initial velocity being 5m/s and decreasing by about 10m/s², v reaches 0 in 0.5 seconds. this time is spent moving at a velocity of between 0 and 5m/s, deceleration happens linearly. average speed upwards is 2.5 m/s. *0.5s is 1.25m.

[@afa4770]

Good explanation thanks a lot

[@crocopie]

Hi there. 4:37 may not be a good example in real life because dropped packages must be parachuted while airborne so that the packages would not be be damaged. A better example would be releasing bomb 💣 into an enemy structure :D.

[@joshuadilao1496]

I dont know if its just me but 2:38 I got 5.4 as an answer for maximum height instead of 1.28

[@rats1740]

same here

[@aveinmovil]

Try to do the operation by hand. If the mistake doesn't pop up for you ask again.

[@getknowledgeaboutmanything633]

Superb,great!!!!!

[@norjanajalel9077]

Life saver 😌😌😌

[@codex7299]

God bless you🙏🏾🙌🏾

[@godot5643]

when will you upload on the topic of quantum mechanics..?

[@ProfessorDaveExplains]

gotta finish classical physics first, but then it's modern physics right after that! so i would say in about three months.

[@yosefrabinow9788]

thanks so much, your videos saved me from failing my physics regent!

[@FreyaChristina]

Hello Professor Dave, I read that the acceleration due to gravity during a free fall is 9.8 but When it is thrown upwards its negative

[@ProfessorDaveExplains]

it's always negative! because the acceleration occurs in the negative direction, towards the earth.

[@EREN-he9jl]

that is because gravity is negative... but since it is thrown upward WHICH IS POSITIVE .. so basically.. negative times positive is negative.. that is why ..

[@khalifakhalifa3902]

You are the best

[@nguyentuanlinh4584]

can i have a question? I always wonder why a is negative when a ball is thrown upward?

[@ProfessorDaveExplains]

acceleration due to gravity is always downward, which is the negative direction

[@nguyentuanlinh4584]

@@ProfessorDaveExplains Thank you very much for the useful lesson.

[@online_class_with_ajibola]

What can I say? Thank you. Thank you and Thank you

[@Cap.doc111]

The conclusion of the whole video is in the first 40 seconds : practice a lot

[@joy4467]

4:29 here why a is -9.8 m/s^2

[@abdelhamidahbane6322]

in the ending comprehension test, Why did you consider the time calculates as a peak time and then multiply it by two ??? isn't it itself the whole hanging time ? I am confused !!

[@abdelhamidahbane6322]

Oh NO NO I got it now, I was wrong. I used the displacement equation instead of the velocity equation....it makes sense now, THANKS Prof, you are the best

[@ranisjohnclienta.1854]

Time: 1.8026 DisplacemeDisplacement:31.866 Is this correct?

[@udaypersonal8434]

double the time

[@sshere16]

Amazing ❤❤

[@MsPslater]

can you do some examples and show how to do the calculations without a calculator?

[@Namjoonsthighs]

1:35 There is actually an equation for this, t = u/g . When I used this I have gotten them same answer but in a -ve form. May I know why this formula doesn't apply? Or did I use the wrong values?

[@jonesnamakhwa9281]

I thank a lot my professor I get something

[@gurgferguson292]

1:36 am studying for Kinematics test, feeling better

[@justtorecordd6708]

ok look thank you alot for everything but for the future if possibe add more quistions at the end so i make sure of my way of solving

[@GermaniaceezTV]

congrats to 1M subs

[@vionamarieVelasco]

shortcut for time flight timeflight = [Vi•sin(theta)/g] 2

[@alexishunt3752]

I used the equation change in y = (viy)(t) + 1/2(a)(t2) and used the quadratic equation to solve for t = 4.928s. Why didn’t this way work?

[@sarastemkar7835]

this equ is for dist/displacement equ contains two unknown if you are solving for time

[@moiseslobopvh]

Hello teacher. How can I find the shooting angle of a ball to hit a basketball hoop, if I have the speed, gravitational acceleration and vertical and horizontal distances? I can't deduce an equation to find the angle when the target is above the launch point.

[@abegailcamacho6003]

Can someone please explain to me how (0 m/s)² = (5.0 m/s)² + 2(-9.8 m/s²) turn into x = 1.28 m?? I watch the video a couple of of times but still can figure it out how did that happen......

[@jamaicanipot-nipot5210]

same prob haha

[@gabrielwongso2309]

(5.0 m/s)² ÷ 2(9.8 m/s²) 👍

[@Thesaviorsway]

I was able to get time but my error for displacement was half using average velocity formula. I then realized you multiply time by velocity in x direction to get total distance if velocity is the same. if velocity changes from initial to final you take the average and multiply by time to get distance.

[@samij8639]

Why horizontal and vertical velocities 17.7 instead of 25 as it is given to us?

[@ProfessorDaveExplains]

you have to do the trigonometry! the calculation is shown. check out my tutorial on projectile motion for a more thorough explanation.

[@gautamchettiar4150]

Toooo Gooood!!!!

[@MrBits_0]

how did you get the 4.95s?

[@inspiringer6418]

I have to do a problem to find the initial velocity but I don't know the acceleration either. All I know is that the final velocity is 0 and the displacement is 60 meters.

[@Mellow429]

If teachers/education system taught in this way(simpler, quicker, basic cartoons, straight to the point) Everyone would have a college degree bc I feel school/college/education would be tremendously cheaper and easier to access which would make our economy so much better. I don't understand our "system"

[@garyhenderson5256]

i need your help with what math to use to calculate the ballistics for a basic artillery game i’m wanting to write in BASIC. The variables are how many bags of powder, angle of the barrel, wind direction and wind speed. The playfield is a very basic random 2 dimensional terrain made up of a line drawn across the screen and random placement of your fort and the opposing fort and you take turns firing back and forth guessing how many bags of powder and what angle to point the cannon

[@avililies]

I hate that when solving the problem is skipping some important steps, like how did you get that answer while mine is nothing like that?? What did you do first?? Did you multiply then yada yada yada.

[@davis4537]

One the first problem, can someone explain how he is getting 1.28m. I keep getting 5.4.

[@kennethgabriel2234]

divide the initial velocity with the acceleration after multiplying it by 2

[@itssohotinhere4615]

i keep on getting 0.26😭😭

[@itssohotinhere4615]

OH THERES SQUARED ON THE FORMULA MB

[@itssohotinhere4615]

but like how did the sign become m? like i get it we r looking for the dastance but like when u manually do it, it makes me cancel both of the m/s^2 of the numerator and denominator?

[@Ishimweniyoelysee]

I really need direct chat with you Prof! I am Bachelor's degree graduand for your support!

[@nicbaeten]

How to calculate the corner that I have to shoot with a air rifle that the pellet escape the barrel with 300m / sec and has a weight from 0,49gr. until it fal back in to the barrel and not 20m further by the neighbors Because the turning speed of the earth? Traveltime about 5 sec.