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# As/ Expt/ G/ Joe

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### As/ Expt/ G/ Joe

1. 1. Determine g Ticker timer
2. 2. Apparatus and materials <ul><li>weight </li></ul><ul><li>Elastic cords for accelerating weight </li></ul><ul><li>Rod for attaching elastic cord to weight </li></ul><ul><li>Ticker-timer with power supply unit </li></ul><ul><li>Ticker-tape </li></ul><ul><li>Sellotape </li></ul>
3. 3. Diagram of the experiment
4. 4. Procedure <ul><li>Thread a length of ticker-tape through a ticker-timer and attach the end to a weight.   Release the weight from. Loop one end of the elastic cord around a rod attached to the weight. Practice doing this.   </li></ul>
5. 5. <ul><li>Choose and cut through a dot near to the start of the tape. Do this when the weight is travelling quite slowly but the dots are far enough apart to clearly distinguish one from another. </li></ul><ul><li>  Count ten dot-to-dot spaces and cut the tape, through a dot, again. You have cut a 'ten-tick-tape' </li></ul>
6. 6. <ul><li>Count 40 more dot-to-dot spaces along the tape. Then cut the next 10 dot-to-dot spaces to make another ten-tick-tape. </li></ul><ul><li>Draw a horizontal line, as a time axis, on a piece of paper. Glue your tapes, vertically and 10 centimetres apart, so the bottom of each tape touches this axis. This 10 centimetres represents 1 second.   </li></ul>
7. 8. <ul><li>Draw a vertical axis anywhere to the left of the first tape. This is a velocity axis. </li></ul><ul><li>Mark a scale, in centimetres per second, on your vertical axis. Each vertical centimetre on your axis represents 5 centimetres per second.   </li></ul>
8. 9. <ul><li>Use your velocity axis to help you to work out the first velocity and the second velocity. You can call these u and v . (Remember that u comes before v in the alphabet, just as the first velocity comes before the second.) </li></ul><ul><li>  Work out the average acceleration of the weight during the time between the two tapes. Acceleration is 'rate of change of velocity'. It is equal to the change in velocity divided by the time. Average acceleration = change in velocity/time taken . </li></ul>
9. 10. <ul><li>The change in velocity is the difference between the two velocities, v - u . The time between these two tapes is t , which in this case is 1 second. </li></ul><ul><li>Draw a straight line between the centres of the tops of the tapes. Draw a horizontal line from the centre of the top of the first tape. Draw a vertical line through the top of the second tape. You have made a right-angled triangle. The length of the base of your triangle, using the units of the horizontal axis, is 1 second.   </li></ul>
10. 11. <ul><li>Find the gradient of the line connecting the tops of the two tapes. Measure the height of the triangle, using the units of the velocity axis, which are centimetres per second (cm/s). Divide the height of the triangle, in centimetres per second, by the base, in seconds. This gives you the average acceleration in centimetres per second per second (cm/s2). </li></ul><ul><li>So we get the value of g. </li></ul>