1. The Professional Development Service for Teachers is funded by the Department of Education and Skills under the National Development Plan Verification of the Principle of Conservation of Momentum Using a ticker timer T.H.

2. PDST Resources for Leaving Certificate Physics 2 Apparatus

3. PDST Resources for Leaving Certificate Physics 3 The ticker tape timer  This is connected to 12 V AC.  It prints 50 dots per second on a strip of ticker tape paper.  Each dot is printed 1/50 of a second after the one before it.

4. PDST Resources for Leaving Certificate Physics 4 Precautions  Clean the runway with spirits to remove any dust or debris.

5. PDST Resources for Leaving Certificate Physics 5 Precautions  Adjust the slope of the runway until the dots are equally spaced when a single trolley is given a quick push.

6. PDST Resources for Leaving Certificate Physics 6 To see if you’ve compensated enough for friction:  give a trolley a slight push  and see if the dots are equally spaced.

7. PDST Resources for Leaving Certificate Physics 7 Set up the apparatus as in the photograph.

8. PDST Resources for Leaving Certificate Physics 8 Method  Give Trolley A a push and release it immediately.  It will collide with Trolley B and the pins and cork will ensure that they stick together.

9. PDST Resources for Leaving Certificate Physics 9 Method  Calculate the speed of Trolley A and the speed of the combined trolleys from the ticker tape.

10. PDST Resources for Leaving Certificate Physics 10 Conservation of momentum  In the absence of external forces:  the total momentum before the collision is equal to the total momentum after the collision.

11. PDST Resources for Leaving Certificate Physics 11 Conservation of momentum Thus

12. PDST Resources for Leaving Certificate Physics 12 Method  Find the mass of trolley A.  Convert to standard units.  (Write the result down.)

13. PDST Resources for Leaving Certificate Physics 13 Method  Find the mass of trolley B.  Convert to standard units.  (Write the result down.)

14. PDST Resources for Leaving Certificate Physics 14 Find the velocity of trolley A from this tape

15. PDST Resources for Leaving Certificate Physics 15 Answer

16. PDST Resources for Leaving Certificate Physics 16 Find the velocity of the combined trolleys.

17. PDST Resources for Leaving Certificate Physics 17 Answer

18. PDST Resources for Leaving Certificate Physics 18 Use these results to see if the experiment verifies the principle of conservation of momentum.

19. PDST Resources for Leaving Certificate Physics 19 Results

20. PDST Resources for Leaving Certificate Physics 20 Conclusion  The total momentum before the collision equals the total momentum after (to two significant figures.)  This experiment verified the principle of conservation of momentum to two significant figures.

21. PDST Resources for Leaving Certificate Physics 21 Further Work  Repeat the entire experiment, adding weights to either or both trolleys.