Ticker Timers allow us to measure the speed and acceleration of moving objects. They are becoming obsolete due to improvements in technology, such as high speed cameras and radar cameras used by police, however, the fundamental principals which they work by allow for a very detailed analogue measurement of speed and acceleration.
They work by using an AC (Alternating Current) power supply to turn an electromagnet on and off, which makes a little hammer hit some carbon paper which transfers a dot onto a testing strip of paper.
In Australia our Electrical frequency of our grid is 50hz which means that the hammer taps 50x per second OR once every 0.02 seconds. This means that we can observe how fast something is moving with a “refresh rate” of 0.02s between each moment which can be measured in cm.
NOTE: Be sure to convert your final units into m/s once you find your cm/s
Measurement of the acceleration due to gravity with a ticker timer
The aim of this experiment is to measure the acceleration due to gravity using a ticker timer.
- A ticker timer
- A 12V ac power supply
- Ticker tape 1 – 1.5m (depending on desk height)
- A small mass (say 50g)
- A retort stand, boss and clamp, Scissors and ruler
- Fix the mass to one end of the ticker tape using the crocodile clip or hook.
- Connect the power supply. Fit the tape into the timer. Hold onto the free end of the tape and switch on the power supply.
- Release the tape. The pull of gravity on the mass will accelerate the tape through the timer.
- Repeat the experiment two further times (or until each person has one copy to put in their book)
Discussion and Conclusion
- Cut up your tape into segments of five SPACE lengths. Keep them in order and glue into book.
- Measure the length of both the first ‘five spaces’ and the last ‘five spaces’.
- Work out the acceleration due to gravity from the formulas:
- Repeat this for the other two trails.
- Work out an average value for the acceleration due to gravity.
- What do you think is the main reason for this experiment not being very accurate?