A cannonball is fired horizontally from the top of a tall cliff at a speed of 39.2m/s.

a. Using a coordinate system where the top of the cliff is the origin, the +x direction is horizontal in the direction the cannonball is fired, and the +y direction is vertically upward, write down the velocity vector for the cannonball as a function of time in i- j-k notation. [Be sure to include units.]

Three seconds have elapsed since the cannonball was fired, and it has not yet hit the ground.

b. Find the speed and direction (measured as an angle with the horizontal) of the cannonball at this moment.

c. Find the position vector (in i-j-k notation) of the cannonball at this moment.

d. Find the rate at which the cannonball's speed is changing at this moment.