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Displacement formula question 
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#1
Oct711, 03:57 PM

P: 21

Hey, first post (:
Was just wondering why the formula for distance is x = ½ at^{2} if v = at and x = vt then why is it ½ when you substitute in a? x = distance v = velocity t = time 


#2
Oct711, 04:08 PM

Mentor
P: 40,718




#3
Oct911, 09:09 AM

P: 1,421

Nice post. Very good how you defined the variables
x = vt means that there is no acceleration so a = 0, and you have to plug into the whole formula and not just part of it. ( ie with a=0 and using only half an equation, x = (1/2) at^2 becomes x = 0 ) The actual forms of the equation are: x1x0 = v0 x t with no acceleration ie a=0 Eq 0 With constant acceleration x1x0 = ( v0 + v1)/2 x t Eq 1 where ( v0 + v1)/2 is the average velocity Also v1 = at + v0 Eq 2 sustitute equation 1 into 2 x1  x0 = ( v0 + at + v0 )/2 x t or x1  x0 = v0 t + (1/2) a t^2 Eq 3 the final equation of for rectinear motion with constant acceleration is (v1)^2  (v0)^2 = 2a(x1x0) Eq 4 Hope that helps. you have to plug into the whole formula  not just part of it. 


#4
Oct1011, 05:16 PM

P: 21

Displacement formula question
Thanks good sirs



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