Spring potential energy example (mistake in math)

[albertwengy]

Real answer is sqr(19.6) which comes out to be 4.42m

[hahs4]

thank you sal, you really saved my ass (again), thanks

[MrDlnggorton]

I think k 1/2=5

[Alexiepower]

haahah now i wont forget "mass/maths general hospital" :D

[vampirates26]

mgh....haha mass/maths general hospital HAHAHA :))

[JonBlizzle2]

I lol'd at the 4kg ice cube xD

[swss12]

the kinetic energy just needs to be >0 for it to go around the loop..... it does not need to be 2g.

[RayMeel]

did anyone else get 7m for the REAL answer?

[Stratocaster1111]

@RayMeel it's (2g)^1/2 = 4.43m

aka the square root of 2g

[purplepick1]

wow thanks :P very very helpful!!!

[charly3nity]

There is an error in the calculations from the very start, P(initial) = 1/2 K*x^2

P(initial)= 1/2 *10 N* x^2

P(initial)= 5 X^2 not 10 X^2.............

AND THANK YOU FOR UPLOADING APPRECIATE IT VERY MUCH!!!

[skyfaze]

well its not that big of a math mistakes u just do 10/5 = 2 so sqrt(2*9.8)

[surroundsound5000]

Why not pop in one of those little bubble notes when the mistake is made, just in case people are questioning their maths...

[CaliDollxo]

@surroundsound5000 that takes the fun out of it! :)

[shortygtx]

Thank you sooo much!!!! I can only dream of my university professor giving me such a clear and understandable explanation. I must say you're truly gifted as a teacher.

[dustin432321]

to beleve im only 13 and i still get this!!!

[megaelliott]

you didn't multiply 10 by 1/2.

[emilyr1212]

1/2 10 was not carried out. only 10*x^2. It should have been 5*x^2.

[grinreper0]

im in college right now and (modesty aside) im fairly good in phisics, i did well on my first mid term but on my second mid term (tommorow) i wasnt feeling real sure, ur videos cleared everything up in a why neither my book nor cramster could! thank you so much! your a brilliant teacher and awsome in phisics!

[jrBunny1979]

Thank you so much for making and posting these videos.

[HotActionProductions]

is it Dero?

old buddy, thers forty-eleven ways to solve this problem.

a long time ago Kalkalators used to be a human.

do you know anything about diesels?

[0x7F800000]

are you sure that there was only ONE mistakes...

this all looks like total crap, all units are totally messed up, it starts with "k=10" (bananas or what? or maybe rather N/m -.-? ) and ends with enerGy measured in "G" which is something like m/s² or whatever...

omg o_O?

most confusing explanation of such a simple problem i can imagine...

[nagzul]

lol the "g" stands for gravity.

[inzanozulu]

The only thing he didn't tell the units of was K, notice it makes very little difference (none, actually). Also notice that v^2 is measured in m^2/s^2, whereas mas is measured in kg, so in the end, his unit does equal a Joule.

Besides, if you are -at all- familiar in the material, you should know that units and whatnot are mostly a formality.

"Don't be stingy with your units"

[09wilsonm]

Thank you so much khanacademy. I'm actually understanding this!

[anava84]

I got X=4.47m at initial PE=5x^2 and gravity=10m/s^2

[Sheogorath64]

I'm vince welke, your friendly neighborhood filipino math major.

[megaelliott]

I got X=4.43m

[youngnuts202]

I think that you did the math wrong. PE= .5kx^2

k= 10. so PE=5x^2

I haven't done this in physics in a while. So I'm not entirely sure.

[khanacademy]

You're right. It should be 5. I need to be more careful

[youngnuts202]

Thank you for spending the time making these wonderful videos. When I go to college, I'll probably have to take a year of physics. Now that I know such videos exist, I will be using yours as a great example. I'll recommend them to my friends as well!

We all make mistakes though. So no harm done!