4.17. A particle is projected in the air at some angle to the horizontal, moves along parabola as shown in the figure, where x and y indicate horizontal and vertical directions respectively. Show in the diagram, direction of velocity and acceleration at points A, B, and C.


Hint: Velocity will always be tangential to the curve in the direction of motion and acceleration is always vertically downward.
Step 1: Draw the diagram

Consider the adjacent diagram in which a particle is projected at an angle θ

vx = Horizontal component of velocity = v cos θ = constant.
vy = Vertical component of velocity =v sin θ