How do I solve this difficult physics problem? Please explain in steps, if possible?

Question

A speedboat starts from rest and accelerates at +2.01 m/s2 for 7.05 s. At the end of this time, the boat continues for an additional 5.70 s with an acceleration of +0.518 m/s2. Following this, the boat accelerates at -1.49 m/s2 for 8.75 s.

(a) What is the velocity of the boat at t = 21.5 s?

_____m/s

(b) Find the total displacement of the boat.

______ m

Answer 1

Solving this is simple arithmetic.  The various changes in velocity are the products of the accelerations and the times, and once these are multiplied out, you simply add the results.  You also need to compute the distances for each acceleration leg; do this by determining the average velocity during the interval (the first, plus the last, divided by 2), and multiplying by the time.  You then add up the distances.