If a ball is given a push so that it has an initial velocity of 5 m/s down a certian inclined plane, then the distance it has after $t$ seconds is $s(t)= 5t+3t^2$.
(a) Find the velocity after 2 sec.
(b) How long does it take for the velocity to reach 30 m/s?

(a) $v(2)=$ m/s
(b) $t=$ seconds