Question

a simple Model (model 1)of distance,d meters,fallen in time t seconds by free-fall skydiver is d(t)=4.9t^2
a. sketch the model
b. a different model (model 2) for the distance travelled by a skydiver is d(t)=4.9t^2-0.1t^2.sketch a graph of this function

Answer 1

I think your second model has a typo. Why not just say d(t) = 4.8t^2 ?

At any rate, you can plot multiple curves on the same axes here

http://www.wolframalpha.com/input/?i=plot+y%3D4.9t%5E2%2C+y%3D4.8t%5E2

If the second equation has to be tweaked, adjust it and fix the graphs.