Without air resistance, a projectile fired horizontally at 8 km/s from atop a mountain will
A) return later to its starting position and repeat its falling behavior.
B) accelerate downward at g as it moves horizontally.
C) trace a curve that matches the earth's curvature.
D) all of these
E) none of these

Question

Quizplus · Accepted Answer

A projectile fired horizontally at 8 km/s (which is close to Earth's orbital velocity) without air resistance will indeed accelerate downward at 9.8 m/s^2 due to gravity (B), trace a curve that matches the Earth's curvature because its horizontal velocity is sufficient to keep it in orbit (C), and therefore, it will return to its starting position and repeat its falling behavior, effectively orbiting the Earth (A). Thus, all of these statements (D) are correct.

Without Air Resistance, a Projectile Fired Horizontally at 8 Km/s