# Average velocity equation?

• Feb 12th 2013, 01:30 PM
sakonpure6
Average velocity equation?
If I am given the acceleration of 4 m/s(sqaured) and a total time of 12 m/s what formula would i use to find the average velocity?
• Feb 12th 2013, 01:37 PM
ILikeSerena
Re: Average velocity equation?
Erm... 12 m/s is not a time.

Anyway, average velocity is $\bar v = {\Delta x \over \Delta t}$.
See e.g. wiki.
• Feb 12th 2013, 01:40 PM
ILikeSerena
Re: Average velocity equation?
Apparently you need a couple of assumptions.
Initial speed of zero and acceleration until 12 m/s or something like that.
With assumptions like that you could calculate $\Delta x$ and $\Delta t$.
• Feb 12th 2013, 01:41 PM
sakonpure6
Re: Average velocity equation?
Quote:

Originally Posted by ILikeSerena
Erm... 12 m/s is not a time.

Anyway, average velocity is $\bar v = {\Delta x \over \Delta t}$.
See e.g. wiki.

sorry about that, but in my question I am not given the displacement!
Here is the question:

An airplane maintains a constant acceleration of 4 m/ssquared E as it speeds up from 16m/s t0 to 28 m/s E

what is the av. velocity?
• Feb 12th 2013, 01:48 PM
ILikeSerena
Re: Average velocity equation?
Quote:

Originally Posted by sakonpure6
sorry about that, but in my question I am not given the displacement!
Here is the question:

An airplane maintains a constant acceleration of 4 m/ssquared E as it speeds up from 16m/s t0 to 28 m/s E

what is the av. velocity?

Ah well, in that case you can simply take the average of the initial and the final speed.
$\bar v = {v_{initial} + v_{final} \over 2}$

Alternatively, you can calculate $\Delta t = {\Delta v \over a}$ and $\Delta x = v_{initial} \Delta t + \frac 1 2 a (\Delta t)^2$.
But you'll get the same result.
• Feb 12th 2013, 02:01 PM
sakonpure6
Re: Average velocity equation?
thank you, much appreciated. Im new and some info needs to be sorted >.<!
• Feb 12th 2013, 04:22 PM
HallsofIvy
Re: Average velocity equation?
Quote:

Originally Posted by ILikeSerena
Ah well, in that case you can simply take the average of the initial and the final speed.
$\bar v = {v_{initial} + v_{final} \over 2}$

This is correct as long as the acceleration is constant as is, of course, the case here.

Quote:

Alternatively, you can calculate $\Delta t = {\Delta v \over a}$ and $\Delta x = v_{initial} \Delta t + \frac 1 2 a (\Delta t)^2$.
But you'll get the same result.
• Feb 18th 2013, 08:49 PM
LanellePalmer
Re: Average velocity equation?
Apparently you need a couple of assumptions.

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