Free Fall Acceleration Direction · PhysicsBowl 2015 #5
Physics · mechanics
Problem
An object initially is moving upward while in free fall. Which one of the following choices best represents the direction of the object's acceleration during its flight?| Object moving upward | Object at peak of motion | Object moving downward |
|---|---|---|
| (A) Upward | Zero | Downward |
| (B) Downward | Zero | Downward |
| (C) Upward | Downward | Downward |
| (D) Downward | Zero | Upward |
| (E) Downward | Downward | Downward |
Intuitive explanation
In free fall, gravity is the only force acting on the object, so its acceleration is always downward—regardless of which direction the object is moving. Many students confuse the direction of motion with the direction of acceleration: an object moving upward can still be accelerating downward (slowing down), and this acceleration never changes. The key insight is that acceleration depends on forces, not velocity.
Intuitive explanation
In free fall, gravity is the only force acting on the object, so its acceleration is always downward—regardless of which direction the object is moving. Many students confuse the direction of motion with the direction of acceleration: an object moving upward can still be accelerating downward (slowing down), and this acceleration never changes. The key insight is that acceleration depends on forces, not velocity.