Projectile Motion on the Moon

Steps:

• The stone is thrown horizontally, so initial velocity is horizontal, but after release, no horizontal forces act due to no atmosphere or friction.
• Vertically, only the Moon's gravity acts, providing a constant downward force since gravity is uniform near the surface.
• Horizontal acceleration is zero, so horizontal force is zero.
• Vertical acceleration is constant (g_moon), so vertical force is constant.

Why C is correct:

• Newton's first law: no net horizontal force means zero horizontal force; vertical force is mg, constant by uniform gravitational field.

Why the others are wrong:

• A: Horizontal force is zero, not non-zero.
• B: Horizontal force is zero, and vertical force is constant, not decreasing.
• D: Vertical force is constant, not decreasing.

Final answer: C