EMPA practice answers

A2 EMPA practice questions and sample results

Section 2

l /m	h /m	h /m	h /m	Mean h /m
0.860	0.370	0.365	0.375
0.801	0.503	0.504	0.492
0.724	0.668	0.673	0.672
0.651	0.809	0.812	0.808
0.553	0.945	0.946	0.949

https://www.researchgate.net/publication/252262271_Period_of_an_Interrupted_Pendulum

https://www.youtube.com/watch?v=MEgPkkQSt7s

1. For the largest  value of l what is the range of h ? 0.010m
2. For the largest  value of l what is the percentage uncertainty of h ?1.35%
3. For the smallest value of l what is the uncertainty of h ? 0.002mm
4. For the smallest value of l what is the percentage uncertainty of h ? 0.21 approx
5. Draw a graph of your results on the grid provided.
6. What is the pattern shown by these results, and how accurate are they? How do you know?line goes through the points, ranges are small, points close to line of best fit
7. What are the main sources of uncertainty in this experiment? measuring height with ruler as bob is round, 
8. What equations describe the energy changes involved in this experiment? mgh to 1/2mv squared
9. A pendulum swings from a support post and another post is added to interrupt its swing. We desire to know the maximum height at which the pendulum will perform a full loop around the post. The pendulum requires both potential and kinetic energy in order to complete a full loop. Therefore, it will never be able to return to its height of release while completing a full loop. Ultimately, the pendulum has enough energy to complete a full loop when interrupted at a height equal to two-fifths its initial height of release.
10. How could you use your data to verify the above statement? calculate gradient and compare to that value - should equal 0.4 I think, but probably won't!
11. A student performs a similar experiment but instead measures the maximum height the pendulum reaches once it hits the rod and swings around it.  What would you expect the student to find?height it reaches = height it is released from - directly proportional
12. Which of your measured values could you use to verify this relationship? Need hight it reaches, or you could work that out by subtracting h from total length of pendulum and use the l as well.
13. Describe the motion of the pendulum on each side of the rod. SHM and then circular motion
14. What is the gradient of the graph of the above results?0.4 maybe, or 0.6.