Investigating Newton’s Second Law Using the Horizontal and Vertical Ball Launcher – Which Ball Hits the Ground First?
Newton’s Second Law links force, mass, and acceleration — but it also explains one of the most surprising results in physics: a ball fired horizontally and another dropped vertically hit the ground at the same time, provided they start at the same height. This simple but elegant experiment helps students connect equations of motion to real-world outcomes.
The Experiment
Using a ball launcher, one ball is released vertically downward while another is launched horizontally from the same height. Students use strobe flash or high-speed video to measure the time each takes to hit the ground.
Observation:
Both balls land simultaneously — despite one moving sideways.
This happens because horizontal motion and vertical motion are independent. Gravity accelerates both balls downward at the same rate (about 9.8 m/s²), regardless of their horizontal speed. Mass has nothing to do with the equation and forces that work at right angles to one another are ignored.
The Science
The experiment illustrates the core of Newton’s Second Law:
Gravity provides the same downward force on both balls, giving them equal acceleration.
The horizontally launched ball has an additional velocity component, but that motion does not affect how long gravity takes to pull it to the ground.
This principle lies behind projectile motion and explains why a bullet fired from a gun and one dropped from the same height (in a vacuum) would hit the ground together.
Skills Highlight
-
Applying to explain motion in two dimensions
-
Recording and analysing motion data using sensors or video frames
-
Understanding the independence of horizontal and vertical motion
-
Using experiments to test theoretical predictions
Why It Works in Teaching
This investigation transforms abstract equations into a striking visual demonstration of Newton’s laws. Students often predict that the fired ball will take longer to fall — until they see the data prove otherwise. It’s one of those memorable experiments that makes physics click.
No comments:
Post a Comment