If a car accelerates uniformly from rest at 3.2m/s(2). when the car has traveled a distance of 40. meters, its speed will be.

I tried to use equation

v-u/a= t

but there r two unknowns in this

t and v...

how to solve it

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- Sep 17th 2011, 06:49 PMmoonnightingalehow to calculate final velocity of car
If a car accelerates uniformly from rest at 3.2m/s(2). when the car has traveled a distance of 40. meters, its speed will be.

I tried to use equation

v-u/a= t

but there r two unknowns in this

t and v...

how to solve it - Sep 17th 2011, 06:53 PMmoonnightingaleRe: how to calculate final velocity of car
Ok i have solved in this way

since S=vt, so t=S/v

Equating both equations

v-u/a= S/v

v/3.2=40/v

v(2) = 128

**v= 11.31 m/sec**

is this approach correct - Sep 18th 2011, 12:38 AMmr fantasticRe: how to calculate final velocity of car
You're expected to be familiar with the uniform acceleration straightline motion formulae. I sugest you go back to your class notes or textbook and review this topic more thoroughly.

For the question you posted, use $\displaystyle 2as = v^2 - u^2$, substitute the given data and solve for v. - Sep 18th 2011, 03:28 AMHallsofIvyRe: how to calculate final velocity of car
No, it is not because the formula v= S/t applies only to

**constant**velocities.

Rather, use v= at and [/tex]S= (1/2)at^2[/tex]. (Since the car started from rest, your "u" is 0.)

In this problem, those equations become v= 3.2t and $\displaystyle 40= 1.6t^2$. Solve the second equation for t and put that into the first equation.