1. Using the CPO timer All of the items below should be in the “Little Black Box of Science”

2. CPO Timer Inputs It doesn’t make a difference what color (red or blue) phone cord you use for input A or B. However, the A cord/photogate should be the top photogate.

3. CPO Computer

4. Photogate uses an invisible beam of infra-red light to start and stop the timer.

5. The 5.0 cm car “wing” triggers the Photogate

6. The 5.0 cm wing start and stops the timer

7. The timer works like 3 internal stopwatchs Time thru A Time thru B Time from A to B No times shown

9. Using the CPO Timer Turn on the A light only, if you want to know how long it took the car to go through photogate A. Turn on the B light only, if you want to know how long it took the car to go through photogate B. Turn on the A & B lights, if you want to know how long it took the car to go from photogate A through photogate B.

10. Using the CPO Timer On interval mode, you never have to push the reset button. It automatically resets every time you send the car down. The timer “remembers” all 3 times when you send the car down the ramp. To retrieve the times, just push the corresponding A & B buttons.

11. Resolution The smallest interval that can be measured.

12. The timer has a resolution of (.0001 seconds) That’s ten thousandth’s of a second Interval Mode TenthHundredthThousandth Ten Thousandth

13. Accuracy Accuracy: how close a measurement is to the true value.

14. The CPO Timer & Photogates are accurate to the + or -.0005 of a second.

15. Precision: How close together repeated measurements are. Which group is more precise? Group A (s)Group B (s).0238.1487.0296.1482.0201.1479.0193.1485.0333.1483

16. “IFR” Index Finger Release This will make a big difference on the precision of our data! Good “IFR” technique should give us a precision of + or -.0005 seconds

17. Accuracy & Precision