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a rocket-powered sledge accelerates at 35ms^-2 and takes 1.6s to pass through a 60 m section of a test track. Find the speed at which it entered the section. what was its speed when it left.

 Oct 18, 2017
 #1
avatar+98125 
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I'm not great at Physics, but I think we can use these equations

 

(vf )^2  =( vi )^2 + 2ad     (1)    and

 

vf  = vi + a*t      →  (vf)^2  =  (vi)^2 + 2vi *a*t + (a*t)^2   (2)

 

Equate  (1)  and (2)

 

( vi )^2 + 2ad  =  (vi)^2 + 2vi *a*t + (a*t)^2      simplify

 

2ad  =  2vi *a*t + (a*t)^2      fill in what we know

 

2(35)60  = 2( vi) (35)(1.6)+ (35 * 1.6)^2

 

4200 = 112* vi  + 3136      subtract   3136 from both sides

 

1064  =  112*vi      divide both sides by 112

 

9.5 m/s =  vi  = initial velocity

 

And

 

vf  = vi + a*t

 

vf  = 9.5 + 35*1.6  =  65.5 m/s  = final velocity

 

 

cool cool cool

 Oct 18, 2017
edited by CPhill  Oct 19, 2017

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