December 9th, 2016, 01:30 AM  #1 
Member Joined: May 2016 From: Ireland Posts: 94 Thanks: 1  particle accelerating
a particle passes point P with speed 10 m/s and moves in a straight line with uniform acceleration to a point Q . in the first second of motion after passing P it travels 14 m. in the last 5 seconds of motion before reaching Q it travelled 7/10 of PQ. find the acceleration of the particle and the distance from P to Q. i found out the acceleration by using uvast equations. s=ut +.5at^2 14=10(1)+.5(a)(1)^2 a=8 . however i dont know how to find the distance

December 9th, 2016, 08:31 AM  #2 
Math Team Joined: Jul 2011 From: Texas Posts: 2,546 Thanks: 1259 
let $d$ be the total distance between P and Q; $t+5$ = total time; $v$ = velocity at the start of the last 5 seconds of travel three equations ... $v = 10 + 8t$ $\dfrac{3d}{10} = \dfrac{t}{2}(10+v)$ $\dfrac{7d}{10} = v \cdot 5 + 4 \cdot 5^2$ three unknowns ($v$, $t$, and $d$) ... solve the system for $d$ I get $d = 500 \, m$ 
December 9th, 2016, 09:00 AM  #3 
Member Joined: May 2016 From: Ireland Posts: 94 Thanks: 1 
ye i understand now thanks


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