There are two ways to live your life - one is as though nothing is a miracle, the other is as though everything is a miracle.

- Einstein

Questions to ponder

1. Describe the motion of a falling body.

2. What are the forces affecting the motion of a falling body?

3. In the absence of air friction, how would the acceleration of a large mass compare with the acceleration of a small mass?

Free Fallin'

Video Instruction

showmethephysics.com

I. Motion of objects moving freely under the force of gravity.

Freefall - falling where the only force is gravity

 "Do the examples below show freefall?"

Guy jumps from the 3rd floor onto a tree. Wild stuff

Galileo (1564 - 1642)

Credit: Original portrait by
Justus Sustermans painted in 1636.

[Flash]
Rutgers U.

Click on the Arrow

home/videos/ForceMotion/massFreeFall5.htm

Free Fall - D vs. t Plot
Rutgers U.

Distance and Time
Rutgers U.

[Flash]

Show Me The Physics

showmethphysics.com

 All objects falling near the surface of the earth accelerate at a constant rate  of -9.8 m/s2 (neglecting air resistance)

g = - 9.8 m/s2

Rounding off g we get -10 m/s2

Ex) An object thrown upward at
+40 m/s

| Flash |

Show Me The Physics

An object is thrown up at a velocity of 30 m/s

About how long will it take to hit the ground?

6 seconds

 V (m/s) Time (sec) 30 0 20 1 10 2 0 3 -10 4 -20 5 -30 6

Draw the V vs t Plot

 Acceleration due to gravity is CONSTANT near the surface of any planet  or moon.

Label the slope pictured above
that could be Jupiter? Moon?

Top Line: Jupiter

Bottom Line: Moon

D vs t - free fall

A ball is thrown upward.
What's the acceleration
due to gravity at the peak?

-9.8 m/s2

AP Question

Ex) Compare the displacement of an object dropped during its first second with its  displacement after 3 seconds.

Δd = Vit + 1/2aΔt2

Δd = 1/2aΔt2

9 times greater