# Help! (1 Viewer)

#### Yellow

##### Member
can somebody please help how to find acceleration in terms of velocity. it's probably easy but i can't find it anywhere!

#### mannnnndy

##### chocoholic
do u mean like the special result where a = d/dx(1/2v^2)?

#### Yellow

##### Member
i know how to integrate an acceleration equation using that and vdv/dx.

but how do you find acceleration in terms of velocity by differentiating?

#### school-spew

##### New Member
you get acceleration by differentiating v, if v is a function of t
a=dv/dt

if v is a function of x
a=dv/dx(1/2 v^2)

i hope i got the whole function thing right, because i always mix them up. when i say v is a function of x i mean v=2x+4 or whatever (just in case i didn't get the terminology right)

hope that helps but..

#### Yellow

##### Member
hmmm alright but how do you get a = 2v + 4 by differentiating? i can see how you get a = 2t + 4 and a = 2x + 4 but what about
a = 2v + 4?

#### mannnnndy

##### chocoholic
ive never actually seen an equation where a = 2v + 4 or whatever. i had a look at the 3u & 4u syllabus and did not see it anywhere. r u sure it even exists?

#### Lazarus

##### Retired
If you found v as a function of x, and then found a as a function of x, you might be able to rearrange the former and substitute for x into the latter.

Could possibly do it with time instead of displacement as well.