physics: free fall

Section 3: Falling Objects

Overview

Understanding motion of objects under gravity.

Key Objectives

  1. Relate free falling bodies to constant acceleration.

  2. Calculate displacement, velocity, and time for free-falling objects.

  3. Compare motions of different objects in free fall.

Free Fall Basics

  • Definition: Free fall occurs when only gravitational force acts on an object.

  • Free-fall acceleration (g): 9.81 m/s² (Earth).

  • Misconception: Heavier objects fall faster.

    • Truth: All objects fall at the same rate without air resistance.

Velocity and Time

Tabulation:

  • t=0s: 0 m/s

  • t=1s: -9.8 m/s

  • t=2s: -19.6 m/s

  • t=3s: -29.4 m/s

  • t=4s: -39.2 m/s

  • t=5s: -49.0 m/s

Key Equations

  1. Ax = vᵢ t + ½ a t²

  2. v = vᵢ + at

    • Acceleration: -9.81 m/s² during free fall.

Important Concepts

  • Same acceleration for all objects regardless of mass.

  • Displacement is proportional to time squared (t²).

  • Acceleration is constant even at the highest point of trajectory (-9.81 m/s²).

Sample Problems

  1. Volleyball Drop: Given initial velocity = 6.0 m/s (upward), displacement = -2.0 m, find time to hit the ground.

  2. Flowerpot Drop: Drop from 25.0 m, find velocity before impact and time to reach the ground.

Conclusion

Free fall shows constant acceleration irrespective of mass. Ignore air resistance for accurate understanding of kinematic equations and gravity's role.