User Name Remember Me? Password

 Physics Physics Forum

January 25th, 2017, 11:07 AM   #1
Member

Joined: Feb 2014

Posts: 91
Thanks: 1

Calculating the Acceleration

So I'm stuck on another homework problem.

Quote:
 It took 5 s to come to a halt for a car to travel 200 m. Find its initial velocity and acceleration.
There is no equation this time to help me out and I'm unsure if I'm able to write this as function of time at this moment. Could I get another hint? January 25th, 2017, 11:32 AM #2 Senior Member   Joined: Sep 2015 From: USA Posts: 2,366 Thanks: 1272 you can always write $s(t) = \dfrac {a t^2}{2} + v_0 t + s_0$ $v(t) = a t + v_0$ so if you are given a time $T$ and distance $D$ you can write $s_0=0,~s(T)=D$ $0 = a T + v_0$ $v_0 = -a T$ and substituting this back in $s(t) = \dfrac {a t^2}{2} + (-a T) t$ $s(T) = \dfrac {a T^2}{2} + (-a T) T$ $D = -\dfrac {a T^2}{2}$ $a = -\dfrac{2 D}{T^2}$ $v_0 = - a T = \dfrac{2 D}{T}$ and you can plug your values in Thanks from topsquark Last edited by romsek; January 25th, 2017 at 11:54 AM. January 25th, 2017, 11:36 AM   #3
Math Team

Joined: May 2013
From: The Astral plane

Posts: 2,073
Thanks: 842

Math Focus: Wibbly wobbly timey-wimey stuff.
Quote:
 Originally Posted by The_Ys_Guy So I'm stuck on another homework problem. There is no equation this time to help me out and I'm unsure if I'm able to write this as function of time at this moment. Could I get another hint?
Call the initial position to be at $\displaystyle x_0 = 0 \text{ m}$. You know that the final velocity $\displaystyle v = 0 \text{ m/s}$. (Of course $\displaystyle x = 200 \text{ m}$.)

$\displaystyle x - x_0 = \frac{1}{2} (v - v_0) t$

Solve for $\displaystyle v_0$. Can you finish?

-Dan Tags acceleration, calculating Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post SophiaRivera007 Physics 2 December 29th, 2016 09:56 PM atari Calculus 4 March 6th, 2016 08:59 AM Mike7remblay Physics 3 February 1st, 2012 06:48 PM MasterOfDisaster Physics 4 June 14th, 2011 01:44 PM imcutenfresa Calculus 5 October 7th, 2009 02:51 PM

 Contact - Home - Forums - Cryptocurrency Forum - Top      