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

2. Apparatus
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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.
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4. Precautions
Clean the runway with spirits to remove any dust or debris.
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5. Precautions
Adjust the slope of the runway until the dots are equally spaced when a single trolley is given a quick push.
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6. To see if you’ve compensated enough for friction:
give a trolley a slight push
and see if the dots are equally spaced.
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7. Set up the apparatus as in the photograph.
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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.
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9. Method
Calculate the speed of Trolley A and the speed of the combined trolleys from the ticker tape.
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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.
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11. Conservation of momentum
Thus
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12. Method Find the mass of trolley A. Convert to standard units.
(Write the result down.)
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13. Method Find the mass of trolley B. Convert to standard units.
(Write the result down.)
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14. Find the velocity of trolley A from this tape
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15. Answer
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16. Find the velocity of the combined trolleys.
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17. Answer
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18. Use these results to see if the experiment verifies the principle of conservation of momentum.
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19. Results
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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.
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21. Further Work
Repeat the entire experiment, adding weights to either or both trolleys.
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