The velocity of an object in meters per second is v(t) = 40 − t2, 0 ≤ t ≤ 6. Find the velocity v(4) and acceleration a(4) of the object when t = 4.

v(4) = ??
a(4) = -8

I got the -8, I can't get the v(4) though, any help?

/e v(4) wouldn't be 32 would it?

This post was edited by FiestaBeast on Sep 19 2013 10:01pm

do you understand what it means to have the equation for v(t)? it means you know what v(t) is for any t. so if t = 4, just plug in 4 for t

so 40-(8) = 32?
I put that down but got marked wrong
/e got it.

This post was edited by FiestaBeast on Sep 19 2013 10:11pm

im pretty sure a(4) is actually -2 if v(t) = 40 - 2t

This post was edited by khemist on Sep 20 2013 12:40pm