May 8th, 2017, 12:21 PM  #1 
Member Joined: May 2016 From: Ireland Posts: 92 Thanks: 1  journey
a particle moves 13m in the first second and 43m and 83m in the fourth and eight seconds. are the distances consitent with the supposition that it is moving with constant acceleration i am trying to solve this using uvast equations. for each bit i know the time,distance 
May 8th, 2017, 01:38 PM  #2 
Senior Member Joined: Sep 2015 From: CA Posts: 1,207 Thanks: 615 
$s(t) = \dfrac {a t^2}{2} + v_0 t + s_0$ the phrasing you've used makes it sound like $s_0=0$ $s(1) = \dfrac{a}{2} + v_0 = 13$ $s(4)=8a+4v_0 = 43$ $s(8) = 32a + 8v_0 = 83$ $\begin{pmatrix}\dfrac 1 2 &1 \\8 &4 \\ 32 &8\end{pmatrix}\begin{pmatrix}a \\ v_0\end{pmatrix} = \begin{pmatrix} 13 \\ 43 \\ 83 \end{pmatrix}$ Ignoring the 3rd row for a moment we solve the system using the first two rows to obtain $a=\dfrac 3 2,~v_0 =\dfrac{55}{4}$ now we check if the third point fits $83 \overset{?}{=} 32\left(\dfrac 3 2\right) + 8\left(\dfrac{55}{4}\right)$ $32\left(\dfrac 3 2\right) + 8\left(\dfrac{55}{4}\right) = 11048 = 62 \neq 83$ So no these points are not consistent with constant acceleration 
May 8th, 2017, 11:00 PM  #3 
Member Joined: May 2016 From: Ireland Posts: 92 Thanks: 1 
Thanks very much


Tags 
journey 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Math Quest. And so my journey begins  InkSprite  New Users  1  December 30th, 2016 03:41 PM 
lorry journey  markosheehan  Applied Math  4  December 16th, 2016 02:05 PM 
Journey Through Spivak's Calculus  russphelan  Calculus  26  October 17th, 2016 11:14 AM 
Thomas Anderson  Journey to the big examinations.  ThomasAnderson  New Users  4  January 25th, 2015 09:23 AM 