A student claims that as a projectile rises, its horizontal speed decreases because its vertical speed decreases. In ideal projectile motion, the horizontal and vertical components evolve independently. Which statement best refutes the claim?
- Gravity provides only vertical acceleration, so stays constant. (correct answer)
- Gravity acts opposite the motion, so it slows both components equally.
- As decreases, energy transfers into , increasing it.
- Horizontal speed must decrease because the projectile is turning.
Explanation: This question challenges misconceptions about velocity changes in rising projectiles. Independence ensures that vertical deceleration from gravity does not affect horizontal motion. Horizontal velocity stays constant, as no horizontal acceleration exists. The student's claim wrongly couples the components, assuming vertical slowdown impacts horizontal speed. Choice C misrepresents energy transfer between components, which doesn't occur in independent motions. To refute such claims, emphasize Newton's laws: acceleration requires force, and gravity provides none horizontally.