IGCSE Physics: Principle of moments and weights on bridges

[@AbdulRahman-pr4vo]

Im here after 8 years it was posted

[@liln1ggatoucher]

lol me too

[@Zachalogian1-ks1hi]

10 years haha

[@kanokochan8671]

I have a question that even i dont understand

[@somerandomguy1853]

mood.

[@thwin7953]

Our school teaches O level physics and chem to freshmen and THIS VIDEO HELPED ME A LOT. I swear I don't even feel like crying or burning my textbook anymore. TYSM!

[@walnut9921]

Thank you so much for this! Great help before the exam!!

[@stephendube5519]

very useful indeed.

[@kaylinbphillips]

Thank you

[@NadaJBfan]

So glad you remind us of the PoM during the video.

[@m33sh50]

hi i was just wondering for the last question if you were not given force a or b and only force w with the length of w to a and b. how would you then work out force a/b????

[@diptihehehe2768]

A uniform metre rule pivoted at 30cm is in equilibrium. A mass if 40kgf is suspended at 25cm from the fulcurm. Find the mass of the metre rule.

[@evansmugwe5103]

Do u still want the answer

[@zarghunadurrani3366]

@@evansmugwe5103 i do. Can yog please do it?

[@techiehelper1114]

Yesssss Mr Saunders

[@SanjayKumar-mu9qo]

thank u very much.. I had no physics tutor and I had this doubt.. thank u

[@amina5684]

so the weight of the bar will be 400N?

[@9501599]

Hi there I am building a model of a railway bascule bridge and I was wondering because the bridge has a length forward of the pivot point and a weight at the rear to counter the forward length, how does the principal of equalibrium work as the bridge rises and lowers. The counter weight has to be calculated based on the PoM as you demonstrated but how is the weight of the counterweight calculated? I sorry if this question is somewhat inane but I am not very good with math and I over think these sort of things but I thought I would ask. Cheers

[@ashrabiassami6674]

Did you figure it out?

[@zuhrajb381]

Thank you very much , was very helpful .

[@natsu3948]

soooo verrryyy helpful

[@harshnagra6194]

Yah

[@hassambukhory3008]

Great job !! Thank you so much ... it really helps ! ☺☺

[@x.x206]

When moments are in equilibrium why cant we use cross multiplication. As in the second example : 20N -> 0.5 and x=40N and then we cross multiply but we dont get 0.25 which is my question? Please anyone answer :)

[@josephchay3491]

Here’s my understanding : It can’t be cross-multiplied because it’s not 0.5/20=x/40 or 20/0.5=40/x which will get you x=1 But it’s 0.5*20=x*40 or vice verse which will give you x=0.25 I hope this helps :)

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[@pakkuadnan]

thanks. very easy to understand. really appreciate it

[@mohfa1806]

Thank you for your beautiful videos...i have question please : in the bridge example , where is the axis of rotation ? , why you consider the location of the box as the axis of rotation being over a straight beam?..thank you

[@yasmeenshaikh7788]

Hey there bud. Principle of moments can also be applied in questions like the bridge one. If you see a similar question like the bridge, if the object appears to be balanced or it is mentioned to be balanced then apply the principle of moments.

[@AshLey-uf6sy]

thank you major help

[@Fasken2]

Interesting

[@ultra_gaming411]

Awesome one.... i liked it +1 sub you rock baby... thankyou

[@michkailrichards8200]

Well done.... Thank you Good job 👏

[@fireflyschapstick]

Thankyou so much this really helped

[@abdullahsheikh715]

tnx

[@sohailjaswar6442]

so helpful

[@surd5876]

2:11

[@juslina_sathguru]

Why do you not use the weight ?

[@RGSPhysicsDepartment]

Not sure what you mean? Which section are you referring to?

[@DannyVampire14]

So, how do you do it if they gave you one force (lets say 500) on a beam and two distances (i.e 2m and 3m) how do you find the clockwise and anticlockwise moments about a and b. I know that the answers are two numbers that add up to 500 because PoM applies but I dont know how to find them out, there's some big equation in the middle. Could u help me?

[@RGSPhysicsDepartment]

+Danny Jones @IGCSE they don't tend to ask this sort of question as a calculation. It's generally a wordy question. However, if you did want to solve it.... 1) You're right that the total upward force would be 500N (as there is no net force) 2) you would take moments about one of the supports and go from there (this is a lot easier with a diagram!) lets say the weight is 2m from the left edge and we'll call the left edge A and the right edge B. The moment for the 500N weight = 500N x 2m = 1000Nm The moment for the support at B = 1000Nm too (PoM) = F x 5m Rearranging gives F = 1000Nm / 5m = 200N This means the force at A = 300N (500N - 200N) and this makes sense as the weight is closer to A so A has to contribute more force in order to attain the same moment as B. Any help?

[@RGSPhysicsDepartment]

+RGS Physics there is an image at this point of the video which should help you visualise it 8:17

[@DannyVampire14]

+RGS Physics thank you so much... You do not know how much I appreciate it, there was this big blank space in the middle of this calculation that I couldn't solve, and you solved for me, thank you so much for your time, you are amazing, and you were great help....Really appreciate it

[@RGSPhysicsDepartment]

No worries

[@Hazeem]

Thanks so much, helped me for an upcoming test tomorrow with someone who strangely sounds exactly like you...

[@punoflife3397]

Thanks

[@iAmori3]

you spelt equilibrium wrong but very very useful

[@liln1ggatoucher]

y is this topic so hard

[@FineTimes01]

0:0

[@joeljose78]

nice light sabre 6:10

[@geo5440]

thanks bro, saved my ass from test tmr

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Today is my paper ... Pray for me 🙏

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Mine is day after tomorrow

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Sigh thank you

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thanks man!

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Next year appearing for the cie exams

[@saadfarooq917]

Thanks a lot :)

[@jakepaterson687]

ok

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Newton mteres!!!!

[@mango8793]

What grade is this video for?

[@padsandprongs9640]

Grade 8

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@@padsandprongs9640 what...country are you from??

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Saudi Arabia

[@legend9872]

@@padsandprongs9640 crazy! I'm learnt this in high school grade 11

[@padsandprongs9640]

Really?!..wow!!!

[@ItsAlekhya_]

Please be clear u were not audible sometimes in the video👎👎👎👎👎👎👎

[@tomwright8784]

🤫

[@Aisha-gd6dq]

Thank you