1. y(t) = 0.0190t3
vy(t) = 3*0.0190t2 → 0.0570t2 If t is in seconds then the 0.0570 must have units m/s3 as the result must be a velocity (m/s). Hence B.) is the result.
2. Put t = 4.52 s into x(t) from your previous question to find X, the distance travelled in the x-direction.
Put it into y(t) above to find Y, the distance travelled in the y-direction.
Then calculate R = sqrt(X2 + Y2)
3. As for 2, but using vx(t) and vy(t) instead.
4. Calculate the angle from tan-1(vy/vx)