Question

how can i explain the graph that maybe used to show the speeds at t=5 and t=7 are equal?
if i was given the equation
a=-5t+30???

Answer 1

a'=-5
|a'|=5
the speed is the same for all t

Answer 2

sorry but i dont get what you did :S
what with Ia'I=5???

Answer 3

He said that the derivative of the function a=-5t+30 is a=-5
now speed is always positive as you cant have negative speed.
so |a|= 5

Answer 4

thanks!!!