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March 28, 2024, 09:46:29 pm

Author Topic: 3U Maths Question Thread  (Read 1230206 times)  Share 

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jamonwindeyer

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Re: 3U Maths Question Thread
« Reply #405 on: August 01, 2016, 08:50:53 pm »
+1
Am I wrong or are the answers wrong?

You are correct, but the answer is correct too!



Using a=1/3 in your formula, the answer comes out! That's where the 1/3 out the front comes from  ;D

conic curve

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Re: 3U Maths Question Thread
« Reply #406 on: August 01, 2016, 08:57:22 pm »
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You are correct, but the answer is correct too!



Using a=1/3 in your formula, the answer comes out! That's where the 1/3 out the front comes from  ;D

I am still confused  ???

RuiAce

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Re: 3U Maths Question Thread
« Reply #407 on: August 01, 2016, 09:16:24 pm »
+1
Hey thanks so much for the reply. I was just wondering, is the time of flight 20 seconds for both particles. because the answers say that for particle A its 20s but for particle B its 10s. You think the answers are wrong?
It would be 10s for particle B simply because it started ten seconds later.

I am still confused  ???
Don't see your point.

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« Last Edit: August 01, 2016, 09:20:35 pm by RuiAce »

jamonwindeyer

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Re: 3U Maths Question Thread
« Reply #408 on: August 01, 2016, 09:23:13 pm »
+1
I am still confused  ???

That's alright! Let me do the integral for you. Do you understand the algebra I applied above? Basically when we factorise out the 9 from the square root symbol, moving it outside that symbol means we must instead write 3 (the square root of 9). Let me know if that's the issue for you and I'll do the full working. Assuming it's the integral itself:



Does that help? What specifically is troubling you?

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Re: 3U Maths Question Thread
« Reply #409 on: August 01, 2016, 09:58:18 pm »
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That's alright! Let me do the integral for you. Do you understand the algebra I applied above? Basically when we factorise out the 9 from the square root symbol, moving it outside that symbol means we must instead write 3 (the square root of 9). Let me know if that's the issue for you and I'll do the full working. Assuming it's the integral itself:



Does that help? What specifically is troubling you?

Yeah I get it now. Thanks Ruiace and Jamon

massive

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Re: 3U Maths Question Thread
« Reply #410 on: August 01, 2016, 10:19:58 pm »
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hey guys for part b, the answers say that the max value occurs when t=1, how the heck do you figure that out??

RuiAce

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Re: 3U Maths Question Thread
« Reply #411 on: August 01, 2016, 10:23:27 pm »
+2
hey guys for part b, the answers say that the max value occurs when t=1, how the heck do you figure that out??


massive

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Re: 3U Maths Question Thread
« Reply #412 on: August 01, 2016, 10:44:48 pm »
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massive

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Re: 3U Maths Question Thread
« Reply #413 on: August 02, 2016, 11:07:17 am »
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how do you show part ii?? thnx!

jakesilove

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Re: 3U Maths Question Thread
« Reply #414 on: August 02, 2016, 12:06:58 pm »
+2
how do you show part ii?? thnx!

Hey! Without doing the actual maths for this question, I imagine that you have to prove 2 things.

a) The particle is initially travelling away from the Origin (at t=0, velocity is positive)

b) The velocity of the particle is always positive (for any t, velocity is greater than or equal to zero)

This means that the particle will never 'turn around' and head back towards the origin, so it will never hit the Origin!

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jamonwindeyer

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Re: 3U Maths Question Thread
« Reply #415 on: August 02, 2016, 12:10:57 pm »
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how do you show part ii?? thnx!

Hey! So I'll expand on Jake's comment and perhaps tackle it a little differently, a little intuitive:



Since the particle starts from rest at x=4, acceleration will always be acting in the positive direction (since there is no negative velocity at the beginning, there can't be later). Therefore, the particle will never return to the origin  ;D


RuiAce

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Re: 3U Maths Question Thread
« Reply #416 on: August 02, 2016, 12:11:07 pm »
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humble mango

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Re: 3U Maths Question Thread
« Reply #417 on: August 02, 2016, 01:00:12 pm »
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Hi again! Thanks for the help last time :) , um, I'm having an issue with permutations and combinations. I don't really get the some number questions and "alternating" questions at all and was wondering if you guys could help me again.
The numbers 1,2,3,4,5,6,7,8,9, are arranged in a straight line. Find the number of possible arrangements if:
i) All the odd numbers occur next to each other.
ii) All the odd numbers occur in increasing order, reading from left to right.


10 people (5 boys and 5 girls) have a birthday party. In how many ways can they be seated if the birthday boy is to be seated between two particular girls.

Sorry for the trouble.

RuiAce

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Re: 3U Maths Question Thread
« Reply #418 on: August 02, 2016, 01:26:48 pm »
+1
Hi again! Thanks for the help last time :) , um, I'm having an issue with permutations and combinations. I don't really get the some number questions and "alternating" questions at all and was wondering if you guys could help me again.
The numbers 1,2,3,4,5,6,7,8,9, are arranged in a straight line. Find the number of possible arrangements if:
i) All the odd numbers occur next to each other.
ii) All the odd numbers occur in increasing order, reading from left to right.


10 people (5 boys and 5 girls) have a birthday party. In how many ways can they be seated if the birthday boy is to be seated between two particular girls.

Sorry for the trouble.


The reason I doubt the accuracy of this answer is because I feel it's invalid - I don't think I've catered for the ordering of the even numbers.
_____________________


« Last Edit: August 02, 2016, 01:28:28 pm by RuiAce »

massive

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Re: 3U Maths Question Thread
« Reply #419 on: August 02, 2016, 01:38:15 pm »
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How do you do part iii, iv, and v   ???