1. ## Displacement

man i really suck at this...

oh im really confused here

so my problem is asking me to find the displacement and average velocity speed and i am given this s=t^2-3t+2, 0 less=t less=2

now how do i find the disp and AVS?? am i suppost to just plugin? or do i use f(t+changet)-f(t)/changet

and if i do use the above... what goes where?

2. Originally Posted by cyberdx16
man i really suck at this...

oh im really confused here

so my problem is asking me to find the displacement and average velocity speed and i am given this s=t^2-3t+2, 0 less=t less=2

now how do i find the disp and AVS?? am i suppost to just plugin? or do i use f(t+changet)-f(t)/changet

and if i do use the above... what goes where?
1. What you have is the displacement time function of a body/partice
or what ever. So if you are asked to find the displacement there is
nothing to do, at time 0<=t<=2 it is:

s(t)=t^2-3t+2.

2. You have to decide what you want for the second part, the average
velocity or the average speed.

The velocity is:

v=ds/dt=2t-3

and so the average velocity is:

v_av=[int(0,2) v dt]/2=(s(2)-s(0))/2

The average speed is:

sp_av=[int(0,2) |v(t)| dt]/2=[ {int(0,1.5) 3-2t dt} + {int(1.5,2) 2t-3 dt}]/2

where we split the integral at t=1.5 because that is where the integrand
(2t-3) changes sign.

RonL