Projectile motion
Before you start
Two balls can land together even when one travels a long way sideways. Horizontal motion and falling are independent here.
The setupThe blue projectile and gold comparison ball start at the same height. With launch angle 0°, both initially have zero vertical velocity. Uniform gravity acts downward; air resistance is absent.
What to do and noticeStart with the horizontal launch. Compare their heights at the same time: x = v₀t, y = h − gt²/2, vₓ = v₀ and vᵧ = −gt. They land after √(2h/g); increasing horizontal speed changes range, not fall time. Angled launches have a different initial vertical velocity.
Predict firstWhich lands first: a horizontal launch or a simultaneous drop from the same height?
Use a controlled comparison to understand independent components.
Prerequisites: Velocity has direction and can be resolved into perpendicular components.Compare with a drop
Predict firstWhich lands first: a horizontal launch or a simultaneous drop from the same height?
Both start with zero vertical velocity and have the same vertical acceleration. Their vertical positions remain equal, so they land together. Horizontal motion changes only the landing position.
How to observe
- Pause at the apex and distinguish vertical speed from total speed
- Set a horizontal launch and compare with a drop from the same height
- Vary speed and gravity to test range and flight time
Model notes
Uniform gravity without air resistance; launch angles are 0° to 85°. Horizontal position is measured from beneath the launch point. Energy is per unit mass in J/kg, with zero potential at ground level.