For this problem, vectors are in 2D. A projectile is fired with muzzle speed 150 m/s and angle of elevation 45 from a position 10 m above ground level. (a) Denote by r(t) the trajectory of the projectile, by v(t) its velocity, and by a(t) its acceleration. Then a(t) = 0, 9.8 for all t and r(0) = 0, 10. What is the value of v(0)? (b) Where does the projectile hit the ground (that is, when is y(t) = 0), and with what speed?