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


Free Fall?



Galileo (1564 - 1642)

Credit: Original portrait by
Justus Sustermans painted in 1636.






Effect of Mass On Free Fall
Rutgers U.



Click on the Arrow



Free Fall - D vs. t Plot
Rutgers U.



Distance and Time
Rutgers U.



(Roll your mouse over this)

St. Mary's H.S. Physics



Gravity/Moon - Feather & Hammer





All objects falling near
the surface of the earth
accelerate at a constant rate
 of -9.8 m/s

(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

| Larger |
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



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


due to gravity
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


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