Homework Help: Instantaneous velocity expression

1. Sep 20, 2004

UrbanXrisis

This is an equation of a position v time graph:

x=342t^4-127t^3+1.87t^2+2.45t

I need to use this expression to find the instantaneous velocity at t=0.000s

2. Sep 20, 2004

arildno

And how is inst. velocity related to position?

3. Sep 20, 2004

Tom McCurdy

take the derivative of the first equation
then just plug in t
and volla you got instantious velocity

Last edited: Sep 20, 2004
4. Sep 20, 2004

UrbanXrisis

x`=1368t^3-381t^2+3.74t+2.45

is that correct?

5. Sep 20, 2004

Tom McCurdy

This is what i got
its in white so you must highlight
$$1368x^3 - 381x^2+3.74X+2.45$$
=2.45=instant velocity

lol
oh t is 0
well this is how you would find instant acceleration at other times
$$4104x^2-762x+3.74$$

sorry I added extra but I am just learning this so I thought it would be good practice.

6. Sep 20, 2004

Tom McCurdy

Oh sorry I guess tex equations don't turn white

7. Sep 20, 2004

arildno

Besides, you used x as the variable rather than t

8. Sep 20, 2004

Tom McCurdy

Darn I was so close to getting it right