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1. Ticker timer Cici Ye AS 3

2. a Fix a ticker timer on one of the edges of a table. b Thread a length of ticker tape through a ticker timer and attach the end to a weight. c Turn on the ticker timer. Release the weight. d When the weight falls onto the ground, turn off the ticker timer. How to use a ticker timer to determine g?

3. e There will be a series of dots on the tape. f Choose a dot near to the start of the tape. Choose the dots which are well-distributed. Measure the distance between the first and the last dot you chose. g Calculate the time out.

4. h Draw a table to record the figures you get. 3 2 1 t /s s /cm

5. i Draw a graph and choose the right dots, which later will be used to do the calculation.

6. j Use the formula s=1/2gt 2 , to work out g=2s/t 2 . k Do this a couple of times, and calculate the average g, which will be more accuracy and reliable.

7. However, there are still possibilities for us to take the wrong readings. a If the weight is too heavy, then there will not be enough dots on the tape. Our readings will be inaccurate. b If the weight is too light, then the dots will be too close, which will also cause inaccurate readings.

8. c There will be systematic and random errors when measure the distance between dots.