Physics 1
Lab #4
Topic: Free Fall
Purpose:
To investigate the motion of freely falling objects and to calculate the
acceleration of gravity.
Equipment:
Free Fall Timing apparatus
Method:
I. Free Fall:
The apparatus has three parts, connected
electronically. The first part is the ball
release mechanism. This is a U-shaped
part that holds a steel ball, and allows a
very small electrical current to run
through the ball. Clamp this part to a
support
rod with a
threeprong
clamp.
The second
part is a
platform,
about the size of a playing card. Place
this under the release mechanism.
The third part is the electronic timer.
Clamp a steel ball firmly in the ball
release mechanism.
Twist the thumbscrew to release the ball. Note where it lands, and
place the platform there. Use a tape measure to measure from the
bottom of the ball to the platform. Record this measurement.
Clamp the ball in the release mechanism again. Turn on the timer and
press "reset." Let the ball go. Record the time that the ball takes to
fall through the distance. Do this two more times for the same
1
distance and average the times.
Repeat this trial for two more distances. Make at least one distance
greater than one meter.
Trial
ΔY
t1
t2
t3
tavg
a
1
2
3
Use these data, and any others you may have to calculate the
acceleration of gravity.
The standard value of the acceleration of gravity is -9.81 m/s2.
Calculate the percent error of your calculated values.
II. Free Fall With Horizontal Velocity
Purpose: To investigate and
compare the motions of two
freely-falling objects, released
at the same time, when one
has horizontal velocity and the
other does not.
Equipment:
Cenco ball launcher
Method:
Clamp the ball launcher to a
support rod. Pull the plunger to the left and lock it down by trapping
the handle between the two pins. Place one steel ball in the groove on
2
the right end of the platform as shown. Choose one of the pierced
balls and place it on the end of the plunger on the left. When you flip
the handle up, the spring will force the plunger to the right. The ball
on the left will fall to the floor and the ball on the right will be pushed
with some force off the platform, to the right.
Confer with your partner about the paths that the two balls will take
when the plunger is released. Draw your prediction below. (You don't
have to worry about velocity here; just show the path of the balls.)
Now confer with your partner and predict whether one ball will hit the
floor before the other one, or if they will hit the floor at the same time.
Explain your reasoning.
Now, flip the handle and observe what happens very carefully. Record
your observations.
3
Repeat this experiment for several different heights.
Do your experimental results agree with your prediction? Explain how
they are different if the results disagree.
4