1. Motion in One Dimension
Falling Objects

2. Free Fall
Free fall – motion of an object falling with a constant acceleration
Free fall acceleration due to gravity is represented by g
On Earth, g=9.81m/s2
It is directed toward the center of the Earth
In calculations, g should be negative (-9.81m/s2)
Free fall acceleration is constant
If there is no air resistance, all objects fall at the same rate

3. Free Fall What goes up must come down
Objects thrown up have to deal with negative free fall acceleration as soon as they are thrown
Eventually, this overcomes the positive acceleration sending them up and returns them to the Earth
At the height of the throw, velocity equals zero for just an instant
Acceleration equals -9.81m/s2

4. Free Fall
When a falling object returns to the height from where it was thrown the velocity is now equal and opposite the initial velocity
Use the kinematic equations from the previous section
a becomes g
∆x becomes ∆y as we change axis

5. Free Fall Form to use when accelerating object has an initial velocity
g=-9.81m/s2
Free Fall
Form to use when accelerating object has an initial velocity
Form to use when accelerating object starts from rest
Δy = ½ * (vi + vf) * (Δt)
Δy = ½ * (vf) * (Δt)
vf = vi + g * (Δt)
vf = g * (Δt)
Δy = vi (Δt) + ½ * g * (Δt)2
Δy = ½ * g * (Δt)2
vf2 = vi2 + 2 * g * (Δy)
vf2 = 2 * g * (Δy)