PhysicsLAB: Freefall: Timing a Bouncing Ball

Procedure

Two students form a team. The first student will use a stop watch to time the number of seconds between bounces and the second student will be the observer of how high the ball bounces. When the designated student drops the ball, the student with the stop watch listens for the sound of the first bounce, starts the stop watch, and then listens for the sound of the second bounce, when he stops timing. The second student observes how high the ball bounces against the backdrop of the brick wall. The height and times are recorded in the data chart. The experiment needs to be repeated for a total of five trials.

Calculate the acceleration due to gravity by using the kinematics equation s = v_ot + ½at² and the givens that isolate the second half of the golf ball's bounce:

v_o = 0
s = -height of bounce
t = ½(the total time on your stopwatch)

Place the results of these calculations in the last column.

Data Table

	stopwatch time between bounces	height	experimental "g"
Trial	(sec)	(meters)	(m/sec²)

1

2

3

4

5

Conclusions

What is your group's average experimental value for "g" based on all 5 trials?

Why should your average experimental value actually only be expressed with a maximum of 2 significant digits?

Using your average experimental value for "g", calculate a percent error against the accepted value, -9.8 m/sec².

Which aspect of the data collection had the least precision: the timing or the ball's height measurement? Support your choice.