Edexcel M3 15th May Post- Exam (UK Spec)

I got 0.452 to 3.s.f :/. That was like 5 marks right? :frown:

Original post by supalape

it was the multiple of the mass of the particle attached to the object when it was suspended

Reply 22

OP

Original post by ilazakristudent

I think they even out in terms of difficulty and the grade boundaries won't change too much tbh, i wish they'd go down though :s-smilie:

oh and btw, only 4 marks???

Rip my A* then :frown:

yeah I remember thinking it was a lot of work for 4 marks

Reply 23

You take moments about A right? Work out the distance from the vertical for each force, multiply by mass, and since its in equilibrium you equate?

Original post by supalape

it was the multiple of the mass of the particle attached to the object when it was suspended

Reply 24

right so. no one got 3/2h for the first question? it was the easiest question in the paper, idk how i managed to get it wrong? ill probably get at least 2 for drawing the dumbass COM table though. i guess.
1. 3/2h
2. 9/11R
3. 4.2, 1.7
4. T is uh mroot3{(w^2a/2)-g/root3)} and then u showed it. what was up with giving the angle from the top of the circle. this question took me more than the whole paper combined?
5. 2 and 71.6, its 71.6 because you had to realise it was resting on the surface from the circular face but we worked out the COM from the vertex, so it was arctan 3/1 not 3/2
K=0.438? and im pretty sure about this because i prepared like hell for the suspending question
it was something like (1cos10-3sin10)cos 10Mg=6sin10KMg?) i took moments about the point where the vertical went through
7? root (3gr)/2
and yeah k is 1/3

(edited 4 years ago)

Reply 25

Bruh, I forgot to bloody multiply (1-3tan10) by cos10 to get the perpendicular distance, given that k isnt 0.890 like most are claiming it to be. I think the correct working in my eyes is as follows,

((1-3tan10)cos10)M=6sin10(kM).

And yeah the first bloody question was piss easy IDK how in gods name I got it wrong in the Exam, I mean i got it afterwards :s-smilie:

Original post by dalliant

right so. no one got 3/2h for the first question? it was the easiest question in the paper, idk how i managed to get it wrong? ill probably get at least 2 for drawing the dumbass COM table though. i guess.
1. 3/2h
2. 9/11R
3. 4.2, 1.7
4. T is uh mroot3{(w^2a/2)-g/root3)} and then u showed it. what was up with giving the angle from the top of the circle. this question took me more than the whole paper combined?
5. 2 and 71.6, its 71.6 because you had to realise it was resting on the surface from the circular face but we worked out the COM from the vertex, so it was arctan 3/1 not 3/2
K=0.438? and im pretty sure about this because i prepared like hell for the suspending question
it was something like (1cos10-3sin10)cos 10Mg=6sin10KMg?) i took moments about the point where the vertical went through
7? root (3gr)/2
and yeah k is 1/3

Reply 26

OP

Original post by dalliant

right so. no one got 3/2h for the first question? it was the easiest question in the paper, idk how i managed to get it wrong? ill probably get at least 2 for drawing the dumbass COM table though. i guess.
1. 3/2h
2. 9/11R
3. 4.2, 1.7
4. T is uh mroot3{(w^2a/2)-g/root3)} and then u showed it. what was up with giving the angle from the top of the circle. this question took me more than the whole paper combined?
5. 2 and 71.6, its 71.6 because you had to realise it was resting on the surface from the circular face but we worked out the COM from the vertex, so it was arctan 3/1 not 3/2
K=0.438? and im pretty sure about this because i prepared like hell for the suspending question
it was something like (1cos10-3sin10)cos 10Mg=6sin10KMg?) i took moments about the point where the vertical went through
7? root (3gr)/2
and yeah k is 1/3

I got everything there except for 5b and c, how did I screw up that question that bad fml. Q1 I remember seeing a 9/8 somewhere but 3/2 also looks familiar, I honestly can’t remember what I got for the final answer. Also I think that tension is wrong because you would end up with a root of root 3 for W but I’m sure you just did a typo or something

(edited 4 years ago)

Reply 27

Im hoping question 1 is only 4 marks :s-smilie:

Original post by supalape

I got everything there except for 5b and c, how did I screw up that question that bad fml. Q1 I remember seeing a 9/8 somewhere but 3/2 also looks familiar, I honestly can’t remember what I got for the final answer. Also I think that tension is wrong because you would end up with a root of root 3 for W but I’m sure you just did a typo or something

Original post by dalliant

right so. no one got 3/2h for the first question? it was the easiest question in the paper, idk how i managed to get it wrong? ill probably get at least 2 for drawing the dumbass COM table though. i guess.
1. 3/2h
2. 9/11R
3. 4.2, 1.7
4. T is uh mroot3{(w^2a/2)-g/root3)} and then u showed it. what was up with giving the angle from the top of the circle. this question took me more than the whole paper combined?
5. 2 and 71.6, its 71.6 because you had to realise it was resting on the surface from the circular face but we worked out the COM from the vertex, so it was arctan 3/1 not 3/2
K=0.438? and im pretty sure about this because i prepared like hell for the suspending question
it was something like (1cos10-3sin10)cos 10Mg=6sin10KMg?) i took moments about the point where the vertical went through
7? root (3gr)/2
and yeah k is 1/3

Reply 28

TheBigBrick

8

Does anyone remember how many marks the last part of the SHM question was worth? Also does anyone remember exactly what it was/how to do it?

Reply 29

WAIT ARE YOU SERIOUS ABOUT THE 3/2H THING. wasnt 9/8 for the distance of the cone from the bottom of O? or something? and my tension is 100% right cause i managed to prove b/ so i probably just couldnt use the keyboard to write what i meant. does anyone want a diagram for the COM k question because im insane like that and remember what i drew. i need reassurance because i REALLY need 100 in this.

Original post by supalape

I got everything there except for 5b and c, how did I screw up that question that bad fml. Q1 I remember seeing a 9/8 somewhere but 3/2 also looks familiar, I honestly can’t remember what I got for the final answer. Also I think that tension is wrong because you would end up with a root of root 3 for W but I’m sure you just did a typo or something

Reply 30

OP

Original post by TheBigBrick

Does anyone remember how many marks the last part of the SHM question was worth? Also does anyone remember exactly what it was/how to do it?

First part was 5 and the second part must’ve been 7ish. I found the period (S) using my value of W and then the time taken for P to travel 0.4m from O using x = asinwt. Then I multiplied it by 4 because in one oscillation it’s within 0.4m of the origin 4 times. I then divided that answer by my value of S, as it said that the time in one oscillation that it’s within 0.4m was k x S

Reply 31

****. i just drew the diagram again and you're right. it's ****ing tan not sin. how many marks would i lose if i wrote sin instead of tan. and listen its (1cos10-3tan10)cos 10Mg=6sin10KMg
you have to times it by cos again to get the perpendicular
if i wrote that but instea of tan i wrote sin. that's 2 lost marks right. one error and one for final answer. **** jesus. was the first question REALLY not 3/2h. are yall sure. ive never got those types of questions wrong. what the **** man.

Original post by ilazakristudent

Bruh, I forgot to bloody multiply (1-3tan10) by cos10 to get the perpendicular distance, given that k isnt 0.890 like most are claiming it to be. I think the correct working in my eyes is as follows,

((1-3tan10)cos10)M=6sin10(kM).

And yeah the first bloody question was piss easy IDK how in gods name I got it wrong in the Exam, I mean i got it afterwards :s-smilie:

Reply 32

OP

Original post by dalliant

WAIT ARE YOU SERIOUS ABOUT THE 3/2H THING. wasnt 9/8 for the distance of the cone from the bottom of O? or something? and my tension is 100% right cause i managed to prove b/ so i probably just couldnt use the keyboard to write what i meant. does anyone want a diagram for the COM k question because im insane like that and remember what i drew. i need reassurance because i REALLY need 100 in this.

Please do draw a diagram! I remember I definitely got it right as I worked backwards after and substituted my answer multiple times, but I can’t remember at all. It could be that you’re right

Reply 33

pretty sure it was 5 marks, and you had to find the amplitude by using the speed which you work out from impulse mv-mu, since v at the end of the amplitude is 0, so I=mu, and then u use that u with v^2=w^2a^ to find out amplitude, find the period and then u use x=asinw(t/4) because it's 0.4m? away 4 times. and you see that the time it's 0.4m within the centre of oscillation is 1/3 of the period.

Original post by TheBigBrick

Does anyone remember how many marks the last part of the SHM question was worth? Also does anyone remember exactly what it was/how to do it?

Reply 34

Height of the cone is 100% 9h/8.

(3h/4)(M+(2M/5))=(M)(h/2)+(2M/5)(h+H/3), where H is the height of the cone.

Original post by dalliant

WAIT ARE YOU SERIOUS ABOUT THE 3/2H THING. wasnt 9/8 for the distance of the cone from the bottom of O? or something? and my tension is 100% right cause i managed to prove b/ so i probably just couldnt use the keyboard to write what i meant. does anyone want a diagram for the COM k question because im insane like that and remember what i drew. i need reassurance because i REALLY need 100 in this.

Reply 35

Yeah bro, these callous mistakes are killing me aswell :s-smilie:

Original post by dalliant

****. i just drew the diagram again and you're right. it's ****ing tan not sin. how many marks would i lose if i wrote sin instead of tan. and listen its (1cos10-3tan10)cos 10Mg=6sin10KMg
you have to times it by cos again to get the perpendicular
if i wrote that but instea of tan i wrote sin. that's 2 lost marks right. one error and one for final answer. **** jesus. was the first question REALLY not 3/2h. are yall sure. ive never got those types of questions wrong. what the **** man.

Reply 36

OP