# Homework Help: I'm struggling on manipulating kinematics

1. Feb 4, 2016

### Rebecca Berger

1. The problem statement, all variables and given/known data
Given the equations X=X0+v0t+1/2at^2 and v=v0t+at, show that an expression for v that has no explicit dependence on time can be written as v=+-√v0^2+2a(X-X0)

2. Relevant equations

3. The attempt at a solution
I thought I would manipulate the first given equation to be X-X0/t = [1/2(v-v0)] but as I got to the end it didn't work. Please help.

2. Feb 4, 2016

### Staff: Mentor

Welcome to the PF.

Please show us in detail your work. We can try to help if you show your work to us.

3. Feb 4, 2016

### cnh1995

Shouldn't this be v=v0+at?
I believe taking square on both the sides of this equation would help.

4. Feb 4, 2016

### Rebecca Berger

I took X=X0+v0t+1/2at^2 and separated v0t because v=v0+at so it can just say vt . I then subtracted X0 from both sides and divided by t on both sides. My final equation was X-X0/t=[1/2(v+v0)]

5. Feb 4, 2016

### Rebecca Berger

Yes, sorry I made a typo

6. Feb 4, 2016

### Rebecca Berger

I manipulated the wrong equation

7. Feb 5, 2016

### vnsridhar

the standard notation is v=u+at and s=ut+1/2*a*t2. Express t=(v-u)/a, substitute in s eqn, simplify and you get the answer. v2-u2=2as.