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MeasurementPhysics is based on measurementWhat is the time interval between two clicks of a counter?
What is the temperature of the air?
What is the speed of typhoon?
Besides watches, can you think up other devices which can help us to measure and record the time and motion?
Can they measure very short time intervals?
1. Set up the ticker-tape timer.
2. Put a length of paper tape through it under the carbon paper disc.
3. Slowly pull the tape for about 5 s (record with stop watch)
4. Count the number of ticks on the tape
5. Calculate the time interval for 1 tick,
There are 246 dots marked on the tape for 5 s. How many ticks do the timer make in 1 second?
For example
In 5 s, 245 ticks are marked.
Number of ticks per second = 245 /5
= 49
A ticker-tape timer -- is basically a vibrator,-- puts black dots on a tape at the rate of 50 ticks per second, 50Hz
A ticker-tape timer -- is basically a vibrator,-- puts black dots on a tape at the rate of 50 ticks per second, 50Hz
The error is due to
1. A miscount of the dots which are too close together2. The reaction time in using the stop-watch.
A ticker-tape timer -- is basically a vibrator,-- puts black dots on a tape at the rate of 50 ticks per second, 50Hz
What is the time between these two adjacent dots?
Time interval between two dots= 1/ 50 s
= 0.02 s
The time interval between 2 adjacent dots on the tape is called a ‘tick’
Time interval between two dots= 1/ 50 s
= 0.02 s
1 tick = 0.02s
By counting the dots marked on the tape, we can work out the time taken.
4 ticks!
Time interval = 0.02s x 4 = 0.08s
According to the distribution of the dots, describe the motions recorded on the following
tapes.
START END
START END
START END
START END
Constant motion
Constant motion
Speed increasing
Speed decreasing
1 .
A t a p e i s p r o d u c e d b y a t i c k e r - t a p e t i m e r w h i c h t i c k s a t a f r e q u e n c y o f 1 0 0 H z .( a ) W h a t i s t h e t o t a l t i m e o f t h e t a p e ?( b ) W h a t i s t h e a v e r a g e s p e e d o f t h e t a p e ?
1.(a)total time = 8 1
100 = 0.08 s
(b)average speed = distance
time = 76
008
.
. = 95 cm s1 = 0.95 m s
1
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