1. When the only factor influencing the motion of an object is gravity
FREE FALL
When the only factor influencing the motion of an object is gravity

2. Who started studying Free Fall?
Galileo Galilei ( )
David Scott
To the moon in 1971

3. Free Fall
This is part of motion in one dimension because now instead of using the X dimension we use the Y dimension
All objects under free fall have an acceleration downward of m/s^2 (g).
For acceleration we can use (g)

4. Practice problem 1
A stone is thrown from the top of a building with an initial velocity of 20.0 m/s straight upward, at an initial height of 50.0 m above the ground. The stone just misses the edge of the roof on its way down.
Determine…
The time needed for the stone to reach its maximum height
The maximum height
The time needed for the stone to return to the height from which it was thrown and the velocity of the stone at that instant
The time needed for the stone to reach the ground
The velocity and position of the stone at t=5.00 s

5. Practice Problem 2
A projectile is launched straight up at 60.0 m/s from a height of 80.0 m, at the edge of a sheer cliff. The projectile falls, just missing the cliff and hitting the ground below.
Find…
The maximum height of the projectile above the point of firing
the time it takes to hit the ground at the base of the cliff
Its velocity at impact

6. Example problem 3
A rocket moves straight upward, starting from rest with an acceleration of m/s^2. It runs out of fuel at the end of 4.00 s and continues to coast upward, reaching a maximum height before falling back to Earth.
Find…
The rocket’s velocity and position at the end of 4.00 s
The maximum height the rocket reaches
The velocity the instant before the rocket crashes on the ground