Projectile motion: constant horizontal velocity

Steps:

• Identify horizontal motion as uniform (no horizontal acceleration).
• Use range formula: horizontal distance = v_x × time.
• Calculate v_x = 18 m / 1.5 s = 12 m/s.
• Mass is irrelevant for kinematic calculation.

Why D is correct:

• D matches v_x = 12 m/s, from range = v_x × t in projectile motion.

Why the others are wrong:

• A: Likely uses total time incorrectly or includes vertical component.
• B: May assume g = 10 m/s² for vertical velocity, ignoring horizontal focus.
• C: Could involve mass in erroneous force calculation, but mass cancels in kinematics.

Final answer: D