Prelim 2016 Maths Help Thread (1 Viewer)

InteGrand · May 16, 2016

eyeseeyou said:
Did anyone help me with Q2 or Q3?

$\noindent Here's how to do your Question 3 (below).$

''3. A particle is moving in a straight line. It starts from a fixed point O on the line and at time t second its velocity v m/s is given by v=2cost
a. Find the first two times when the particle is at rest
b. find the distance travelled by the particle between these two lines
c. Find the acceleration particle when it is at rest''

$\noindent a) Since $v=2\cos t$ for $t\geq 0$, (note this is SHM), the first two times when $v=0$ are at $t=\frac{\pi}{2},\frac{3\pi}{2}$ (the first two positive zeros of cosine).$

$\noindent b) Note that the amplitude of the motion is 2 m. Between two consecutive times when it is at rest, the particle travels half a cycle, which is going to be 4 m. So the answer is 4 m.$

$\noindent Note that $\dot{v} = \ddot{x} = 2\sin t$. The extreme values of the acceleration occur when and only when the velocity is 0 (property of SHM). Since the extreme values of the acceleration are $\pm 2$ $\text{m/s}^2$, this is the answer.$

eyeseeyou · May 17, 2016

COuld someone please try solving my second and last question for me

Thanks

davidgoes4wce · May 17, 2016

davidgoes4wce said:
$$ Q1. v=2t-4$

$When t=0, x=3$

$x=t^2-4t+C$

$x=t^2-4t+3$

$Q1 (b)$

$Q1 (c) x(3)=(3)^2-4(3)+3=0 \ metres$

$Q1 (d) |v|= | \int_{0} ^3 2t-4 \ dt| = | \int_{0} ^2 2t-4 \ dt| + | \int_{2} ^3 2t-4 \ dt|=|-4|+|-1|=5$

$Q 1 (e) a=\frac{dv}{dt}=2$

You might also be asking how I got the intervals for t to be [0,2] and [2,3]. What I did was split the velocity function into two parts, to work out the change in displacement. (The area underneath the velocity function, represents the change in displacement. Here is my screenshot:

davidgoes4wce · May 17, 2016

$Q 2$

$v=t+|t-2|$

$\int_{0} ^2 2 dt+ \int_{2} ^6 2t-2 dt$

$= [2t]_{t=0} ^{t=2} + [t^2-2t]_{t=2} ^{t=6}$

$=4+ 24= 28 \ units^{2}$

davidgoes4wce · May 17, 2016

eyeseeyou said:
Okay here:

5. An object falling from rest in air is suspended to an acceleration x (with 2 dots on top of x)=g-(v/k dash) where g and k are constants and v is the velocity and time t
a. Show that v=gk (1-(e^-(t/k)))
b. What is the greatest speed obtained?
c. What is the greatest distance travelled in the time t=k In 4

Your question 5 I can't understand what you are writing.

I'm assuming you mean:

$\ddot{x}=g-\frac{v}{k'} \ ?$

eyeseeyou · May 17, 2016

davidgoes4wce said:
Your question 5 I can't understand what you are writing.

I'm assuming you mean:

$\ddot{x}=g-\frac{v}{k'} \ ?$

Yes that's right David

eyeseeyou · May 22, 2016

Anyone here know how to type a squareroot on microsfot word?

leehuan · May 22, 2016

eyeseeyou said:
Anyone here know how to type a squareroot on microsfot word?

Google search square root symbol

eyeseeyou · May 22, 2016

leehuan said:
Google search square root symbol

okay ty

eyeseeyou · May 22, 2016

leehuan said:
Google search square root symbol

but that just makes it hard for me to type things up b/c I can't make it 100% accrate

Nailgun · May 22, 2016

eyeseeyou said:
but that just makes it hard for me to type things up b/c I can't make it 100% accrate

what browser do you use?

eyeseeyou · May 22, 2016

Nailgun said:
what browser do you use?

Chrome???

leehuan · May 22, 2016

Just learn to use the ordinary symbol with BRACKETS

eyeseeyou · May 22, 2016

leehuan said:
Just learn to use the ordinary symbol with BRACKETS

k

Shuuya · May 22, 2016

eyeseeyou said:
Anyone here know how to type a squareroot on microsfot word?

Click on Insert --> Equation ---> Insert new equation

You should be able to select the square root symbol from 'Equation Tools' (it's under the heading 'Radical')

eyeseeyou · May 22, 2016

Shuuya said:
Click on Insert --> Equation ---> Insert new equation

You should be able to select the square root symbol from 'Equation Tools' (it's under the heading 'Radical')

did that but couldn't find that shit

Shuuya · May 22, 2016

eyeseeyou said:
did that but couldn't find that shit

Which version of Word do you have?

Nailgun · May 22, 2016

eyeseeyou said:
Chrome???

Install this
https://chrome.google.com/webstore/...editor/dinfmiceliiomokeofbocegmacmagjhe?hl=en

This is what I use to write latex, without having to write latex

Lee used to use it/still does

eyeseeyou · May 22, 2016

2010 or 2013 unsure

leehuan · May 22, 2016

Equations toolbox is for Microsoft word 2010 onwards or something I think.

But yeah it's called "Radical" if you're using Microsoft Word for actual maths purposes.

I'm on Microsoft Word 2015 and it's under the Insert tab - Insert Equation then proceed.

Prelim 2016 Maths Help Thread (1 Viewer)

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