Free Fall vs. Projectile Motion (Lilach Cary, Rob Vondrak)

Author

Lilach Cary, Rob Vondrak

Principle(s) Illustrated

1. Gravity causes objects to accelerate downward and that rate is not impacted by a velocity in a perpendicular axis.

2. Objects in free fall experience acceleration

3. Average speed is the total distance divided by the total time.

Standards

• MS-PS2-2

  • Plan an investigation to provide evidence that the change in an object's motion depends on the sum of the forces on the object and the mass of the object.

• HS-PS2-1

  • Analyze data to support the claim that Newton's second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration

Questioning Script

Prior knowledge & experience:

• Objects fall downward due to gravity.

• Objects that are pushed horizontally fall downward in a projectile motion.

Root question:

• What effect does horizontal motion have on the time an object takes to fall?

Target response:

• Objects in horizontal motion fall at the same rate as an object in free fall.

Common Misconceptions:

• Students typically believe that objects in free fall will fall faster than objects falling with a horizontal motion because they are traveling further out before falling down.

Photographs and Movies