Free Fall

1. Free Fall Chapter 3 Section 3 Mrs. Faria

2. Galileo’s Experiment • Galileo dropped several objects with different weight and from different heights • He concluded that when air resistance is neglected, all objects in free fall had the same acceleration

3. Acceleration Due to Gravity • The acceleration of an object in free fall that results from the influence of Earth’s gravity. • Gravity = 9.8 m/s2 • Comes from the center of the Earth • Differs from planet to planet

4. Acceleration Due to Gravity

5. Acceleration Due to Gravity g = -9.8 m/s2 • Max Height • Velocity is ZERO • Acceleration = -9.8 m/s2 • Way Up • Velocity is decreasing • Speed is decreasing • SLOWER • Acceleration = -9.8 m/s2 • Way Down • Velocity is decreasing • Speed is increasing • FASTER • Acceleration = -9.8 m/s2

6. Maximum Height • What is the velocity of the ball at the top of its flight? • 0 m/s • What is the acceleration of the ball at the top of its flight? • -9.8 m/s2 • What would happen if the both velocity and acceleration are zero at the top of the ball’s flight? • The ball would float.

7. Acceleration Due to Gravity g = -9.8 m/s2 Velocity (m/s) • Way Down • Velocity is decreasing • Speed is increasing • FASTER • Acceleration = -9.8 m/s2 DROP When an object is dropped, the initial velocity is zero.

8. Kinematics Equations • ∆x becomes ∆y • a becomes g

9. Problem Solving (Points to Remember) • Acceleration is always -9.8 m/s2 • At maximum height • Velocity is zero • Acceleration is -9.8 m/s2 • Always let your starting position be zero (up=+ & down = -) • When an object is dropped, initial velocity is zero • When an object is thrown into the air, it must have an initial velocity • Time up is equal to time down • At any given point, velocity up is equal to velocity down. • If the object lands below the starting position, then ∆y is negative. • Velocity going up is always positive, velocity going down is always negative.