
free falling object
Use the position function s(t) = 16t^2 + 1000, which gives the height in feet of an object that has fallen for t seconds from a height of 1000 feet. the velocity at time t = a seconds is given by:
lim s(a)  s(t)
t to a a  t
if a construction worker drops a wrench from a height of 1000 feet, how fast will the wrench be falling after 5 seconds?
the answer is 160ft/sec
but i am not sure how to get there,
this is what i have so far:
16 * 5^2 +1000 = 600
600  (16t^2 + 1000)
5  t
where do i go from here? please help!

600  (16t^2 + 1000
5  t
= (16*t^2 400)/(5t)
= 16(t^225)/(5t)
= 16(t5)(t+5)/(5t)
= 16(t+5)
lim 16(t+5) =160
t>5
This is the velocity hence the negative sign indicating it is moving down
the speed is 160