Free Fall

Objectives1.) define free fall

2.) explain that all falling objects accelerate

3.) agree that all objects fall at the same rate

4.) write the free fall equations

Free Fall

IntroductionFree Fall

• motion caused only by gravity

• all objects fall at the same rate

- works in a vacuum: area with no air

- ignores air resistance

Acceleration Due to Gravity

• is a constant.

• is called g

• is = 10 m/s2 on surface of earth

• is different on the moon, but still constant

Free Fall Equations Key

• vv= vertical velocity (in m/s)

• dv = vertical distance (in meters)

• g = acceleration due to gravity (10 m/s2)• t = time (in seconds)

Vertical Velocity Equation

vv gt

Vertical Distance Equation

2

21 gtdv

Time to Fall Equation

gd

t v2

One more free fall

Worksheet A Free Fall Equations

1.) How fast will a ball be traveling if it falls for 5 seconds?

• Data

• Equation• Math• Answer

• t = 5 seconds

g = 10 m/s2

• vv = gt

• vv = 10(5)

• vv = 50 m/s

2. An apple falls out of a tree and takes 1.75 seconds to strike the ground. How high was the

apple from the ground?

• Data

• Equation• Math

• Answer

• t = 1.75 seconds

g = 10 m/s2

• dv = 0.5gt2

• dv = 0.5(10)(1.75)2

dv = 0.5(10)(3.06)

dv = 0.5(30.6)

• dv = 15.3 m

3. A plane drops a C.A.R.E. package to some needy people in the jungle from a height of 1000 m. How long will it take the package to strike the ground?

• Data

• Equation• Math

• Answer

• dv = 1000 m

g = 10 m/s2

• t = √2dv/g

• t = √2(1000)/10

t = √2000/10

t = √200• t = 14.1 seconds

Free Fall Equations

 Vertical Velocity

Steps

1. Multiply g times time 

Vertical Distance 

  Steps

1. Square time (multiply by itself)

2. Multiply by g

3. Multiply by 0.5

Time to Fall 

Steps

1. multiply dv times 2

2. divide by g

3. Press =

4. Press the square root button

2 vdtg

dv 0.5gt2

vv gt

Key: vv= vertical velocity (in m/s)dv = vertical distance (in meters)

g = acceleration due to gravity (10 m/s2)t = time (in seconds)