How do I do part 2 and 3 here?

Answer 1

[KSSV]

Velocity is nothing but dr/dt i.e. slope. So you have used polyfit and you got the slope already.

Answer 2

[Sam Chak]

Hi @Jonathan Wehner

You have done with 2a and 2c.

2b. Since you have computed the polynomial coefficients in the p vector, then p(1) tells you the velocity (slope), and p(2) gives the initial range (intercept). Natural, this means and in the slope-intercept form, .

3. This part requires you to solve for time t when . I believe that you can solve this algebraic equation easily.