OCR M1 - 31st May 2012 :)

Original post by master y

PP. I don't even have the book! :O

lol tbh i have not even looked at the book during revision, i too am only doin pps.

Reply 101

Original post by samjj8

Hey I need help on this question:

Its from the M1 Jan 2011 Paper question 5... :frown:

I can't seem to find T. It's 2/3... but how? :\

Can someone please go through it with me. :smile:

taking a look now geezer

Reply 102

Original post by samjj8

Hey I need help on this question:

Its from the M1 Jan 2011 Paper question 5... :frown:

I can't seem to find T. It's 2/3... but how? :\

Can someone please go through it with me. :smile:

Ok so, the two equations are

for Q : S = 4.9t^2

for P : S = 4.9t + 2.45t^2

Then we make them equal to eachother, but we have to swap 1 of the equations around:

so it's -4.9t - 2.45t^2 = 4.9t^2

rearrange to find t. it comes out as 2/3.

Can anybody help me why we actually reverse the equation around? I actually don't know but i just know the method...thanks :smile:

Reply 103

I'm hoping the question on velocity or displacement time graphs is ok :/ Is it just me that really hates them??

Reply 104

Original post by As_Dust_Dances_

I'm hoping the question on velocity or displacement time graphs is ok :/ Is it just me that really hates them??

They can only get as hard as making you use the trapezium rule to find a certain time.

just remember for displacement graphs, the gradient is the velocity

for velocity, the gradient is the acceleration

and for the trapezium rule... in the style of pop goes the weasel....

half the sum of the parallel sides, times the distance between them.. that's the way the area goes... of a trapezium...

you're all set :smile:

Reply 105

Nathdragon5

6

Original post by Tyles

They can only get as hard as making you use the trapezium rule to find a certain time.

just remember for displacement graphs, the gradient is the velocity

for velocity, the gradient is the acceleration

and for the trapezium rule... in the style of pop goes the weasel....

half the sum of the parallel sides, times the distance between them.. that's the way the area goes... of a trapezium...

you're all set :smile:

Haha, love the song there :biggrin:

the formula for the trapezium rule is also in the formula booklet if they ask you to find the area of more than one successive trapezium :smile:

although I can bet they won't :smile:

Reply 106

Original post by Nathdragon5

Haha, love the song there :biggrin:

the formula for the trapezium rule is also in the formula booklet if they ask you to find the area of more than one successive trapezium :smile:

although I can bet they won't :smile:

it's surprising how well them lyrics have stuck in my head haha

Reply 107

can someone help me on a qu?

on june 05 qu 7vi, how are we supposed to work out the v of P at t=400?

thanks.

Original post by Tyles

it's surprising how well them lyrics have stuck in my head haha

Reply 108

Original post by ugk4life

can someone help me on a qu?

on june 05 qu 7vi, how are we supposed to work out the v of P at t=400?

thanks.

i'll have a ganders

Reply 109

Original post by Tyles

i'll have a ganders

cheers, im really confused!

Reply 110

jonnny

14

Just wondering guys - if you fail to get an answer for part (i) of a question (eg ypu have no idea at all how to get the answer), if you need to use the answer to part (i) in the next part, can you just make up a random number to use and get error carried forward marks. Just because on quite a few questions it seems that if you can't get the first part of a question you pretty much buggered for the rest of it. cheers

Reply 111

Original post by jonnny

Just wondering guys - if you fail to get an answer for part (i) of a question (eg ypu have no idea at all how to get the answer), if you need to use the answer to part (i) in the next part, can you just make up a random number to use and get error carried forward marks. Just because on quite a few questions it seems that if you can't get the first part of a question you pretty much buggered for the rest of it. cheers

i think that you can get follow through marks for sure in c3 and 4, not too sure about in m1 tho i presume you can.

Reply 112

Original post by ugk4life

cheers, im really confused!

Ok, it sounds tricky. but it's easier than it looks.

so let's do P and Q separately.

for p;

a=0.03
u=16
t=200

solve to find how far P has gone from 200 - 400 seconds. this gives you 3800m
then find out how long it goes from o - 200 seconds, which is t = 200, u = 0, and a = 0.08....

overall you should get P travels 5400m

then, for Q. (600t^2 -t^3) x10^-6
Firstly, i would times out by the x10^-6 just to get it out of the way, it's horrible long fractions, but ohwell!

Then remembering that if we have the velocity, to find the displacement we have to integrate. so intergrate that equation, and put the limits t=400. (and 0 if you want, but it won't make no different)

then find the difference between the two, i get 1000m! hope this was clear..

Reply 113

Original post by Nathdragon5

Haha, love the song there :biggrin:

the formula for the trapezium rule is also in the formula booklet if they ask you to find the area of more than one successive trapezium :smile:

although I can bet they won't :smile:

I don't usually work in trapeziums, I like to split it up into a rectangle and a triangle lol :wink:

Also a trapezium question came up on the jan12 paper so I don't think it will come up this time.

(edited 11 years ago)

Reply 114

Original post by jonnny

Just wondering guys - if you fail to get an answer for part (i) of a question (eg ypu have no idea at all how to get the answer), if you need to use the answer to part (i) in the next part, can you just make up a random number to use and get error carried forward marks. Just because on quite a few questions it seems that if you can't get the first part of a question you pretty much buggered for the rest of it. cheers

It's quite easy to make a stupid mistake in mechanics so I hope that is the case!

Reply 115

Original post by As_Dust_Dances_

I don't usually work in trapeziums, I like to split it up into a rectangle and a triangle lol :wink:

same, but sometimes you have to use it! :frown:

Reply 116

Original post by Tyles

Ok, it sounds tricky. but it's easier than it looks.

so let's do P and Q separately.

for p;

a=0.03
u=16
t=200

solve to find how far P has gone from 200 - 400 seconds. this gives you 3800m
then find out how long it goes from o - 200 seconds, which is t = 200, u = 0, and a = 0.08....

overall you should get P travels 5400m

then, for Q. (600t^2 -t^3) x10^-6
Firstly, i would times out by the x10^-6 just to get it out of the way, it's horrible long fractions, but ohwell!

Then remembering that if we have the velocity, to find the displacement we have to integrate. so intergrate that equation, and put the limits t=400. (and 0 if you want, but it won't make no different)

then find the difference between the two, i get 1000m! hope this was clear..

thanks a lot! just one question, how do you know the acc of the trapezium is 0.03?

in fact dont worry, just seen how you get it - cant believe i didnt see that myself. things like this scare me for the real thing lol.

(edited 11 years ago)

Reply 117

Original post by ugk4life

thanks a lot! just one question, how do you know the acc of the trapezium is 0.03?

in fact dont worry, just seen how you get it - cant believe i didnt see that myself. things like this scare me for the real thing lol.

haha thats alright, just remember that whenever it's a displacement graph, the gradient is the velocity, and when it's a velocity graph, the gradient is the acceleration :smile:

And i have the same fright, like right now I just did that question in under 10 minutes and got it right, in the exam i'm going to forget something and get it all wrong. I know it :frown:

. I need an average of 79 in my last 2 exams to get an A. and c4 is killing me.

Reply 118

Original post by Tyles

same, but sometimes you have to use it! :frown:

hmm, guess i'll have to look over it tommorow.. the kinetics topic is the only thing i'm struggling with really with the time graphs, finding out when something overtakes another etc...

Reply 119