1.  How is free fall acceleration different from regular acceleration you experience in your car?  Name three ways physics is used in your home.

2. TEKS 1A, 2H,J, 3A,D, 4A,B,C

4.  Freely falling bodies undergo constant acceleration  In the absence of air resistance (vacuum) all objects dropped near the surface of a planet fall with the same constant acceleration. This is called free fall.  Free fall acceleration is denoted using the symbol g and at the surface of the earth is g=-9.81m/s 2

5.  Thrown objects experience gravity throughout their entire trip.  At the peak of the object’s height, its velocity is 0m/s  Free fall objects always have the same downward acceleration  The only things that change are the object’s velocity and position

6.  Jason hits a volleyball so that it moves with an initial velocity of 6m/s straight up. If the volleyball starts 2m from the floor, how long will it be in the air before it strikes the floor?

7.  Known  v i = 6m/s  a=g= -9.81m/s 2  ∆ d = -2m  v f 2 = v i 2 +2a ∆ d  v f = v i + a ∆ t  Unknown  ? ∆ t  To find ∆ t, we must first find v f from the first equation. Then, we will use that answer in the second equation.

8. Since ball will be moving toward the floor v f will be negative. So v f = -8.7m/s Rearranging the second formula for ∆t, we get:

9.  Time is always positive  In free fall, acceleration is always due to gravity which is –9.81m/s 2 unless otherwise stated

10.  Practice 2F p.64 all  Section Review p.65 #1-4