Using the CPO timer

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. Photogateuses 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 from A to B Time thru 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 Ten Thousandth Tenth Hundredth Thousandth Interval Mode

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?

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