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8/11/2019 Motion of Freely Falling Objects
http://slidepdf.com/reader/full/motion-of-freely-falling-objects 1/3
Olegario, Kevin A.
BSChE -2
Motion of Freely Falling Objects
Objectives:
To study the motion of free falling objects
To determine the acceleration due to gravity, g.
To derive quantities from the slope and intercept of graphs
To determine if the motion of a falling object changes by varying its mass
Theory:
The free fall is a known example or the most common example of a uniformly accelerated
movement, with an acceleration a = -9.8m/s2 (vertical axis pointing vertically upward). If you
choose the vertical axis pointing vertically downward, the acceleration is taken as + 9.8m/s2. The
kinematic equations for a rectilinear movement under the acceleration of gravity are the same as
any movement with constant acceleration:
(1) v = vi - gt velocity as function of time.
(2) y - yi = ½(vi + v)t displacement as function of time
(3) y - yi = vit - ½gt2
displacement as function of time
(4) v2 = vi
2 -2g(x - xi) velocity as function of displacement
The sub index i denotes initial quantities, g the gravity acceleration and t, the time.
But for this type of motion, the displacement of the object as a function of time is described
mathematically as:
(5) ot + ½gt2
where Vo is the initial velocity of the object. If object if just drop
velocity, Equation (5) becomes
(6) ) ½gt2
8/11/2019 Motion of Freely Falling Objects
http://slidepdf.com/reader/full/motion-of-freely-falling-objects 2/3
Olegario, Kevin A.
BSChE -2
Methodology
Procedure:
A digital balance was used to measure the masses of the small and big steel balls.
A set-up of the free fall sensor was followed on the book. The color-coded cables was connected to its color-coded socket.
Coach 6 free fall activity was clicked in the desktop of the computer.
The small steel ball was attached to the free fall sensor.
The steel ball was released after clicking the Start Button.
The stop button was clicked after the steel ball reaches the sensor.
The time of free fall was determined.
Another trial was done for the same height. The average of the two trials was recorded.
The steps 5 - 9 was repeated for the other heights.
The steps 5-9 was repeated using the bigger steel ball.
The height of fall as a function of t2 of fall was plotted.
The slopes and error in the slopes were determined.
The value acceleration due to gravity and its corresponding error from the slopes of the
two graphs were also determined.
Conclusion
Free fall describes any motion involving a dropped object that is only acted on by gravity and
no other forces. Remember, with free fall we have to ignore any impacts of air resistance on the
object. We're only concerned with the acceleration due to gravity, which is a constant value
of -9.8 m/s^2 and represented by a lower-case g . The reason that two objects of different masses
hit the ground at the same time is because, when an object is in free fall, it is "weightless". This
is because there is no force pushing up on it whatsoever. Since both of these objects are
experiencing the same force, gravitational force (that being -9.8N), then they both will fall at the
same velocity and they will both hit the ground at the exact same time. The only factor that
would change this result is air resistance. For example: if one were to take a feather and a
bowling ball and drop both at the same time, the bowling ball would hit the ground first while
the feather remains floating. This is because the feather is experiencing "air resistance" while the
bowling ball is barely affected. If one were to take this experiment to the moon, the bowling ball
and feather would hit the surface at the exact same time. This is because there is no "airresistance" on the moon. So, just remember that the mass of an object makes no difference when
it is in free fall, because it is basically weightless.
8/11/2019 Motion of Freely Falling Objects
http://slidepdf.com/reader/full/motion-of-freely-falling-objects 3/3
Olegario, Kevin A.
BSChE -2
Application
One application would be a skydiver jumping out of an air plane. As he falls, he accelerates. It is
important, because when you are talking about acceleration, you are also dealing with air
resistance. Thus, knowing the amount of acceleration can be helpful in determining the size of
parachute needed to decelerate to a safe speed for landing.