- #1

ghostanime2001

- 256

- 0

## Homework Statement

A car accelerates at 2.10 m/s

^{2}along a straight road. It passes two marks that are 29.6 m apart at times t=4.10 s and t=4.90 s. What was the car's velocity at t=0?

I'm assuming the car has constant acceleration of 2.10 m/s

^{2}

__Given__

[tex]\Delta[/tex]x = 29.6 m

a = 2.10 m/s

^{2}

v

_{i}= ?

[tex]\Delta[/tex]t = ? (I was thinking it might be 0.8 s because of 4.9 - 4.1 s )

The equation I think I should use is:

[tex]x_{f} = x_{i} + v_{i}\Delta t + \frac{1}{2}a(\Delta t)^{2}[/tex]

[tex]x_{f} - x_{i}= v_{i}\Delta t + \frac{1}{2}a(\Delta t)^{2}[/tex]

[tex]\Delta x= v_{i}\Delta t + \frac{1}{2}a(\Delta t)^{2}[/tex]

solving for [tex]v_{i}[/tex] gives the expression:

[tex]\frac{\Delta x - \frac{1}{2}a\Delta t^{2}}{\Delta t} = v_{i}[/tex]

substitute all the numbers:

[tex]\frac{(29.6) - \frac{1}{2}(1.2)\(0.8)^{2}}{((0.8)}[/tex]

[tex]36.52 m/s = v_{i}[/tex]

Am I right or wrong with this answer? Also, I couldn't check to make sure if its right or wrong because I kept on thinking the initial velocity should be zero and i held on to that and kept on asnwering that on CAPA and so as a result, I used up all of my tries :(

Last edited: