PASCO ME-9207B FREE FALL ADAPTER - Manual (Page 8)

4
Free Fall Adapter 012-05760B
Introduction
The equation of motion for a body starting from rest and undergoing constant acceleration can
be expressed as:
where x is the distance the object has traveled from its starting point, a is the acceleration, and
t is the time elapsed since the motion began.
In order to measure the acceleration caused by gravity, several questions must be answered:
•Is the acceleration constant? If it is, then the distance an object falls will be proportional to
the square of the elapsed time, as in the above equation.
•If the acceleration is constant, what is the value of the acceleration? Is it the same for all
objects or does it vary with mass or size of the object, or with some other quality of the ob-
ject? If it is not constant, how does it vary with time?
In this experiment you will answer these questions by carefully timing the fall of a steel ball
from various heights.
Procedure
1. Set up the Free Fall Timer as described in the SETUP and OPERATION section of this manual.
Use the 13 mm diameter steel ball.
2. Set d, the height from which the ball drops, to approximately 2.0 meters. Measure the distance
as accurately as possible and record the distance in Table 1. Follow the instructions for the
Timer or Computer Interface as given in the “Operations” section. Record the measured time
as t
1
in Table 1. Repeat the measurement at least four more times and record these values as t
2
-
t
5
. Calculate the average of your five measured times and record this value as t
avg
.
3. Set d to 1.75, 1.50, 1.25, 1.00, 0.75 and 0.50 m, repeating step 2 for each value of d. (The
actual value of d need not correspond exactly to the listed values, but be sure you measure it
carefully.)
4. Repeat steps 2 and 3 using the 16 mm steel ball.
Analysis
For each ball, plot a graph of d versus t
avg
2 with d as the dependent value (y-axis). Within the
limits of your experimental accuracy, do your data points define a straight line for each ball?
Was the acceleration constant for each ball?
Experiment: Measuring g
Table 1 Data and Calculations
d (m) t
1
t
2
t
3
t
4
t
5
t
avg
t
avg
2
x =
a 2
2