Ticker Timer

SherryAS 3

Ticker TimerFor the measurement of veloci

ty and acceleration, using timing marks made on a moving paper type by a vibrating ‘ stiker ’. Designed to operate on a 12V 500mA AC supply and uses the mains frequency as its timing standard.

Using Procedure

Thread a short length of ticker-tape through the ticker-timer. If there is a carbon paper disc, make sure the tape goes underneath the disc.

Turn the ticker-timer on for a few seconds. It vibrates rapidly and hits the top of the carbon paper. It makes a lot of dots on the tape, at regular intervals.

Remove the tape from the ticker-timer. If the tape didn't move when the ticker-timer was switched on, then all the dots will be in the same place.

Thread a longer piece of ticker-tape, about 1 metre long, through the ticker-timer. Switch the ticker-timer on. Pull the tape slowly through the ticker-timer.

Check the tape to see if you can see each individual dot, with a space between. We can say that each dot-to-dot space stands for a 'tick' of time.

Thread another 1 metre piece of tape through the ticker-timer.

You need a 'start' signal and a 'stop' signal. These could be handclaps by one of your group or by your teacher. They should be just a few seconds apart. Pull the tape slowly and switch the ticker-timer on at the start signal. Switch it off at the stop signal.

Count the number of dot-to-dot spaces between the start and the stop. That is the time between the signals, measured in 'ticks'.

Use a fresh piece of tape, and a stopwatch or stopclock. Pull the tape through the ticker-timer for 3 seconds. Find out how many 'ticks' there are in 3 seconds. Find out how many there are in 1 second. Work out the time in seconds that is the same as 1 tick.

Cut up the tape every 5 dots and this gives the length of tape that travelled in 1/10 second. Stick the lengths of tape in a book go get the acceleration curve, Alternatively, measure the separation of two sequential dots at the beginning of the tape and again near the end. Count the dots between them and then calculate g by calculating the difference in velocity difference in 0.2s.

e.g. First dots 1 cm apart, 10 dots of tape then dots 5 cm apart gives 200cm/s velocity difference in 0.2s.

g = 200/0.2 = 1000ms-2

If the tape increases steadily in length, then the gradient is constant, and the actual acceleration always matches the sloping line which students have drawn on their graphs. Acceleration is then constant, or uniform. And in that case average acceleration, and acceleration at all times during the motion, are the same. Then: acceleration, a = (v-u)/t.  

All the above are information about Ticker Timer.

From Sherry, AS 3

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