Free Fall Physics

Created by K.Rick

What is free fall?

• Motion under the influence of gravitational force only.

• When you free fall do you fall at a constant rate?

ConstantAcceleration

• Look at the data:

Use the equation above to solve for the acceleration of an object in free fall.

Time (s) Velocity (m/s)

0 0

1 10

2 20

3 30

4 40

What does the 10 m/s2 represent?

a = Δv / Δt

a = v2 – v1

t2 – t1

Is there a relationship between velocity and time because of this acceleration?

Constant Acceleration

Time (s) Velocity (m/s)

0 0

1 10

2 20

3 30

4 40

Can you write this relationship as an equation?

Is there a relationship between velocity and time because of this acceleration?

v = g t

How Fast?

• To find the instantaneous speed of an object in free fall use the following equation:

•V = g t

Check Your Understanding :

• What would be the speedometer reading on a falling rock 4.5 seconds after it drops from rest?

• How about 8 seconds?

How far?

Time (s) Distance (m)

0 0

1 5

2 20

3 45

4 80

5 125

• Can you find the mathematical relationship between time and distance? (hint: don’t forget “g”!)d = ½ g (t2)Find the distance an object will fall after 8 seconds of free fall.

How long?

• Rearrange the distance equation to solve for the time the object falls?T = 2 d / g

How long has this skydiver free fallen if he falls for 80 meters?

d = ½ g (t2)

Check Yourself :

• An object is dropped from rest and falls freely. After 6 seconds, calculate its instantaneous speed and distance fallen.Instan. Speed

V = g t

V= 10 m/s2 * 6s

V = 60 m/s

Distance

d = ½ g t2

d = ½ 10m/s2 * 6s2

d = 180 m

Double Check Yourself :

• An object is dropped from rest and falls freely. After 8 seconds, calculate its instantaneous speed and distance fallen. Distance

d = ½ g t2

d = ½ 10m/s2 * 8s2

d = 320 m

Instan. Speed

V = g t

V= 10 m/s2 * 8s

V = 80 m/s

More Practice

• An object falls a distance of 125m. What is its instantaneous speed just before it hits the ground?

(hint: find t then find v)

FYI: DaVinci’s Parachute

• This is DaVinci’s 1493 parachute design

• This is the modern reproduction of his sketch.

His design is highly functional!