The document discusses the concept of free fall as a type of uniformly accelerated motion, emphasizing that all objects fall at the same rate regardless of mass when air resistance is ignored. It includes relevant formulas for calculating distance and velocity during free fall, with examples illustrating the concepts. Key points include that the acceleration due to gravity is approximately -9.8 m/s², and that the motion exhibits time and speed symmetry.

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FREE FALL

2. Discuss the concept of free fall as an example of
uniformly accelerated motion and derive the relevant
formulas for such motion.
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OBJECTIVES:
Solve problems involving freely falling bodies, addressing
the misconception that heavier objects fall faster than
lighter ones, and reinforcing the understanding that all
objects fall at the same rate in the absence of air
resistance.

3. What is
FREE

4. Which will fall
faster?

5. Acceleration due to Gravity (g) = - 9.8 m/s2
without air resistance

6. Free fall is any motion of a
body where gravity is the
only force acting upon it.
This means no air resistance
or other forces are involved.

7. Free Fall
A feather and a coin
accelerate equally
when there is no air
around them

8. In the absence of air
resistance, all bodies at
the same location above
Earth’s surface fall
vertically with the same
acceleration regardless of
size and mass.

9. Falling objects & air resistance
More air resistance on without
crumpled-up piece of paper
Less air resistance on
crumpled-up piece of paper

10. Acceleration due to gravity
0 s,
1 s,
2 s,
3 s,
4 s,
• During each second of fall, the speed
of a ball changes by 9.8 m/s.
• The change in speed is due to gravity.
• Hence, the acceleration in this case is
called acceleration due to gravity.
𝑔=−9.8m/s2

11. All freely falling objects accelerate at
9.81 m/s2
near the surface of the
earth.
Acceleration (g) = - 9.8 m/s2
due to Gravity
All are pulled down at the same rate
regardless of their mass and direction
of motion. (Ignoring air resistance)
Free Fall

12. The motion of an object
that is thrown upward and
which eventually returns to
its starting point exhibits
two symmetries:
1. Time symmetry and
2. speed symmetry.
Free Fall

13. TIME SYMMETRY means
that the time required for the
object to reach its maximum
height equals the time for it
to return to its starting point.
SPEED SYMMETRY shows
that at any displacement
above the point of release,
the speed of the body during
the upward trip equals the
speed during the downward

15. UNIFORMLY
ACCELERATED MOTION
Vf² = Vo² + 2gd
WHERE:
Vf = FINAL VELOCITY
Vo = INITIAL VELOCITY
g = GRAVITY
t = time
acceleration due to gravity
g = -9.8 m/s2

16. DISTANCE
Dy = Vot + 0.5gt²
WHERE:
Dy = VERTICAL
DISTANCE
Vo= INITIAL VELOCITY
g = GRAVITY
t = time
acceleration due to gravity
g = -9.8 m/s2

17. FINAL VELOCITY
Vf² = Vo² + 2gd
WHERE:
Vf = FINAL VELOCITY
Vo = INITIAL VELOCITY
g = GRAVITY (9.8 m/s2
)
d = DISTANCE

19. Example 1
A ball dropped from a
building has traveled
65.8m. A.) How long will
it take the ball to reach
the ground? B.) What is
its velocity just before it
reaches the ground?

20. ૛(
૟૞.࢓ૡ
ૢ.ૡ࢓/࢙૛
)
GIVEN:
Vo = o m/s d= 65.8 m g= -9.8 m/s2
t = ?
d= 65.8 m
SOLUTION:
Dy = Vot + 0.5gt²
Since Vo = 0 m/s
t = =
t = 3.66 s
2݀/݃
A.) How long will it take the ball to reach the ground?

21. GIVEN:
Vo = o m/s d= 65.8 m g= -9.8 m/s2
Vf= ?
d= 65.8 m
SOLUTION:
Vf² = Vo² + 2gd ; Since Vo = 0 m/s
Vf² = 2gd
Vf = =
Vf = -35.91m/s
B.) What is its velocity just before it reaches the ground?
૛ࢊࢍ ૛(−
ૢ. ࢓
ૡ
࢙૛
)(૟૞. ࢓
ૡ )

22. Example 2
A ball is dropped from rest on a
cliff. a) What is the speed of the
ball in 5 seconds later?
b) What is the velocity of the
ball at this time?
c) How far does it travel during
this time?
d) What is the displacement of
the ball

23. Example 3
A baseball is thrown
straight upward with
an initial speed of 20
m/s. How high will it
go?

24. Example 3
Given: Vo = 20 m/s g= -9.8 m/s2
Vf = 0 m/s d = ?
Solution:

25. Example 4
One second after
being thrown straight
down, an object is
falling with a speed of
20 m/s. How fast will it
be falling 2 seconds
later?

26. Example 4
Given: Vo = 20 m/s g= -9.8 m/s2
t= 2 s
Vf = ?
Solution:

27. THANK YOU!
"The future belongs to those who believe
in the beauty of their dreams."
– Eleanor Roosevelt