1. Another way to measure time...
Spark Timers
Another way to measure time...

2. The Spark Timer

3. Keeping Time
The spark timer makes sparks which leave dots behind on spark tape
The spark timer has two different settings (10 Hz and 60Hz)
Frequency is how often something happens over a time (typically per second)
10 Hz means 10 dots/s and 60 Hz means 60 dots/s
So… Spark timers make motion diagrams.

4. How much time?
To determine length of time for an event that is being timed with a spark timer, you count up the number of dots and divide by the frequency.

5. Getting Data From a Spark Timer
Time: dots/frequency
Displacement: measure between dots
Velocity: displacement/time
Acceleration: Kinematics or velocity/time
the number of dots you use will depend on the event you are timing

6. Constant Velocity
Load the spark tape (about 8 inches long) shiny side up into the machine.
Choose 60 Hz
Turn on the spark timer and pull the tape through the timer at as close to a constant velocity as you can (slow constant velocity is best).
Once you pull the tape completely through the machine, turn off the machine

7. Spark Tape Analysis (Constant Velocity)
Glue the spark tape here
Are the dots roughly evenly spaced?
Determine the total time and measure the total distance between your first and last dots. Then calculate the average velocity

8. Acceleration
Load the spark tape (about 8 inches long) shiny side up into the machine.
Choose 60 Hz
Turn on the spark timer and pull the tape through the timer slowly at first then try to increase your pulling speed
Once you pull the tape completely through the machine, turn off the machine

9. Spark Tape Analysis (Acceleration)
Glue the spark tape here
Is there a region where the dots begin getting spaced further and further apart
Determine the velocity between two consecutive dots (initial velocity), then determine the velocity between a later pair of dots (final velocity). Determine the total time elapsed between the first dot of your first pair, and the last dot of your last pair. With this data calculate average acceleration