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'

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.

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Rutgers U.

Click on the Arrow

Free Fall - D vs. t Plot
Rutgers U.

Distance and Time
Rutgers U.

(Roll your mouse over this)

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St. Mary's H.S. Physics

 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

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St. Mary's H.S. 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

A. Motion diagram for free fall on any planet or moon

 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