Velocity Question?!?

Question

I need some help figuring out this question. My teacher just gave them without explaining them.

1. Kristin rode east along the bike path on her way to the mall. She stopped at the top of a slope before coasting down, accelerating constantly at 0.75 m/s^2 for 24 s. She then applied her brakes and slowed to 10 m/s in 5.0 s.

(a) What was Kristin's velocity after 24s?

(b) What was her acceleration while she braked?

(c) WHat was her displacement after 29s?

Answer 1

a) her initial velocity was 0 m/s at the top of the hill.  After 24 seconds her final velocity is

vf = 0m/s + (.75m/s^2)(24s) = 18 m/s