Projectile Motion Basics

Steps:

• Resolve initial velocity u into horizontal (u cos θ, constant) and vertical (u sin θ, decelerates at g) components.
• Total time of flight t = (2 u sin θ)/g, so time to max height = (u sin θ)/g = t/2.
• Horizontal distance (range) = (u cos θ) * t.
• Vertical velocity changes due to gravity: starts at u sin θ, becomes -u sin θ at landing.

Why D is correct:

• Vertical velocity is not constant; it decreases linearly under constant acceleration g downward (from Newton's second law).

Why the others are wrong:

• A: Horizontal velocity is constant (no horizontal acceleration).
• B: Horizontal distance equals constant horizontal velocity times total time.
• C: Symmetric motion makes ascent and descent times equal, so max height at t/2.

Final answer: D